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Boccella S, Perrone M, Fusco A, Bonsale R, Infantino R, Nuzzo S, Pecoraro G, Ricciardi F, Maria Morace A, Petrillo G, Leone I, Franzese M, de Novellis V, Guida F, Salvatore M, Maione S, Luongo L. Spinal neuronal activity and neuroinflammatory component in a mouse model of CFA-induced vestibulodynia. Brain Behav Immun 2024; 119:408-415. [PMID: 38636564 DOI: 10.1016/j.bbi.2024.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 03/21/2024] [Accepted: 04/16/2024] [Indexed: 04/20/2024] Open
Abstract
Vestibulodynia is a complex pain disorder characterized by chronic discomfort in the vulvar region, often accompanied by tactile allodynia and spontaneous pain. In patients a depressive behaviour is also observed. In this study, we have used a model of vestibulodynia induced by complete Freund's adjuvant (CFA) focusing our investigation on the spinal cord neurons and microglia. We investigated tactile allodynia, spontaneous pain, and depressive-like behavior as key behavioral markers of vestibulodynia. In addition, we conducted in vivo electrophysiological recordings to provide, for the first time to our knowledge, the characterization of the spinal sacral neuronal activity in the L6-S1 dorsal horn of the spinal cord. Furthermore, we examined microglia activation in the L6-S1 dorsal horn using immunofluorescence, unveiling hypertrophic phenotypes indicative of neuroinflammation in the spinal cord. This represents a novel insight into the role of microglia in vestibulodynia pathology. To address the therapeutic aspect, we employed pharmacological interventions using GABApentin, amitriptyline, and PeaPol. Remarkably, all three drugs, also used in clinic, showed efficacy in alleviating tactile allodynia and depressive-like behavior. Concurrently, we also observed a normalization of the altered neuronal firing and a reduction of microglia hypertrophic phenotypes. In conclusion, our study provides a comprehensive understanding of the CFA-induced model of vestibulodynia, encompassing behavioral, neurophysiological and neuroinflammatory aspects. These data pave the way to investigate spinal cord first pain plasticity in vestibulodynia.
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Affiliation(s)
- Serena Boccella
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Michela Perrone
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Antimo Fusco
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Roozbe Bonsale
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Rosmara Infantino
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Silvia Nuzzo
- IRCCS Synlab SDN, Via Emanuele Gianturco 113, 80143 Naples, Italy
| | | | - Federica Ricciardi
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Andrea Maria Morace
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Gianluca Petrillo
- Department of Molecular Medicine and Medical Biotechnology, "Federico II" University of Naples, Via Tommaso de Amicis 95, 80131 Naples, Italy
| | - Ilaria Leone
- IRCCS Synlab SDN, Via Emanuele Gianturco 113, 80143 Naples, Italy
| | - Monica Franzese
- IRCCS Synlab SDN, Via Emanuele Gianturco 113, 80143 Naples, Italy
| | - Vito de Novellis
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Francesca Guida
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Marco Salvatore
- IRCCS Synlab SDN, Via Emanuele Gianturco 113, 80143 Naples, Italy
| | - Sabatino Maione
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy.
| | - Livio Luongo
- Department of Experimental Medicine, Division of Pharmacology, Università della Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy.
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Park KD, Son JY, Kim HK, Kim YM, Ju JS, Jo MJ, Park MK, Lee MK, Ahn DK. Differential Regulation of Intracisternally Injected Angiotensin II-Induced Mechanical Allodynia and Thermal Hyperalgesia in Rats. Biomedicines 2023; 11:3279. [PMID: 38137500 PMCID: PMC10741042 DOI: 10.3390/biomedicines11123279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 12/01/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
The present study examined the underlying mechanisms of mechanical allodynia and thermal hyperalgesia induced by the intracisternal injection of angiotensin (Ang) II. Intracisternal Ang II injection decreased the air puff threshold and head withdrawal latency. To determine the operative receptors for each distinct type of pain behavior, we intracisternally injected Ang II receptor antagonists 2 h after Ang II injection. Losartan, an Ang II type 1 receptor (AT1R) antagonist, alleviated mechanical allodynia. Conversely, PD123319, an Ang II type 1 receptor (AT2R) antagonist, blocked only thermal hyperalgesia. Immunofluorescence analyses revealed the co-localization of AT1R with the astrocyte marker GFAP in the trigeminal subnucleus caudalis and co-localization of AT2R with CGRP-positive neurons in the trigeminal ganglion. Intracisternal pretreatment with minocycline, a microglial inhibitor, did not affect Ang II-induced mechanical allodynia, whereas L-α-aminoadipate, an astrocyte inhibitor, significantly inhibited Ang II-induced mechanical allodynia. Furthermore, subcutaneous pretreatment with botulinum toxin type A significantly alleviated Ang II-induced thermal hyperalgesia, but not Ang II-induced mechanical allodynia. These results indicate that central Ang II-induced nociception is differentially regulated by AT1R and AT2R. Thus, distinct therapeutic targets must be regulated to overcome pain symptoms caused by multiple underlying mechanisms.
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Affiliation(s)
- Ki-Don Park
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; (K.-D.P.); (J.-Y.S.); (H.-K.K.); (Y.-M.K.); (J.-S.J.); (M.-J.J.)
| | - Jo-Young Son
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; (K.-D.P.); (J.-Y.S.); (H.-K.K.); (Y.-M.K.); (J.-S.J.); (M.-J.J.)
| | - Hak-Kyun Kim
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; (K.-D.P.); (J.-Y.S.); (H.-K.K.); (Y.-M.K.); (J.-S.J.); (M.-J.J.)
| | - Yu-Mi Kim
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; (K.-D.P.); (J.-Y.S.); (H.-K.K.); (Y.-M.K.); (J.-S.J.); (M.-J.J.)
| | - Jin-Sook Ju
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; (K.-D.P.); (J.-Y.S.); (H.-K.K.); (Y.-M.K.); (J.-S.J.); (M.-J.J.)
| | - Min-Jeong Jo
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; (K.-D.P.); (J.-Y.S.); (H.-K.K.); (Y.-M.K.); (J.-S.J.); (M.-J.J.)
| | - Min-Kyoung Park
- Department of Dental Hygiene, Kyung-Woon University, Gumi 39160, Republic of Korea;
| | - Min-Kyung Lee
- Department of Dental Hygiene, Dong-Eui University, Busan 47340, Republic of Korea;
| | - Dong-Kuk Ahn
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; (K.-D.P.); (J.-Y.S.); (H.-K.K.); (Y.-M.K.); (J.-S.J.); (M.-J.J.)
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3
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Nemoto W, Yamagata R, Nakagawasai O, Tan-No K. Angiotensin-Related Peptides and Their Role in Pain Regulation. BIOLOGY 2023; 12:biology12050755. [PMID: 37237567 DOI: 10.3390/biology12050755] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/19/2023] [Accepted: 05/20/2023] [Indexed: 05/28/2023]
Abstract
Angiotensin (Ang)-generating system has been confirmed to play an important role in the regulation of fluid balance and blood pressure and is essential for the maintenance of biological functions. Ang-related peptides and their receptors are found throughout the body and exhibit diverse physiological effects. Accordingly, elucidating novel physiological roles of Ang-generating system has attracted considerable research attention worldwide. Ang-generating system consists of the classical Ang-converting enzyme (ACE)/Ang II/AT1 or AT2 receptor axis and the ACE2/Ang (1-7)/MAS1 receptor axis, which negatively regulates AT1 receptor-mediated responses. These Ang system components are expressed in various tissues and organs, forming a local Ang-generating system. Recent findings indicate that changes in the expression of Ang system components under pathological conditions are involved in the development of neuropathy, inflammation, and their associated pain. Here, we summarized the effects of changes in the Ang system on pain transmission in various organs and tissues involved in pain development process.
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Affiliation(s)
- Wataru Nemoto
- Division of Pharmacology, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai 981-8558, Japan
| | - Ryota Yamagata
- Division of Pharmacology, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai 981-8558, Japan
| | - Osamu Nakagawasai
- Division of Pharmacology, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai 981-8558, Japan
| | - Koichi Tan-No
- Division of Pharmacology, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai 981-8558, Japan
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4
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Smith MT. Nonopioid analgesics discovery and the Valley of Death: EMA401 from concept to clinical trial. Pain 2022; 163:S15-S28. [PMID: 35984369 PMCID: PMC10578428 DOI: 10.1097/j.pain.0000000000002675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 04/22/2022] [Accepted: 04/28/2022] [Indexed: 12/23/2022]
Affiliation(s)
- Maree T Smith
- Centre for Integrated Preclinical Drug Development, School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, Queensland, Australia
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5
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Steckelings UM, Widdop RE, Sturrock ED, Lubbe L, Hussain T, Kaschina E, Unger T, Hallberg A, Carey RM, Sumners C. The Angiotensin AT 2 Receptor: From a Binding Site to a Novel Therapeutic Target. Pharmacol Rev 2022; 74:1051-1135. [PMID: 36180112 PMCID: PMC9553111 DOI: 10.1124/pharmrev.120.000281] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 05/19/2022] [Accepted: 06/27/2022] [Indexed: 11/22/2022] Open
Abstract
Discovered more than 30 years ago, the angiotensin AT2 receptor (AT2R) has evolved from a binding site with unknown function to a firmly established major effector within the protective arm of the renin-angiotensin system (RAS) and a target for new drugs in development. The AT2R represents an endogenous protective mechanism that can be manipulated in the majority of preclinical models to alleviate lung, renal, cardiovascular, metabolic, cutaneous, and neural diseases as well as cancer. This article is a comprehensive review summarizing our current knowledge of the AT2R, from its discovery to its position within the RAS and its overall functions. This is followed by an in-depth look at the characteristics of the AT2R, including its structure, intracellular signaling, homo- and heterodimerization, and expression. AT2R-selective ligands, from endogenous peptides to synthetic peptides and nonpeptide molecules that are used as research tools, are discussed. Finally, we summarize the known physiological roles of the AT2R and its abundant protective effects in multiple experimental disease models and expound on AT2R ligands that are undergoing development for clinical use. The present review highlights the controversial aspects and gaps in our knowledge of this receptor and illuminates future perspectives for AT2R research. SIGNIFICANCE STATEMENT: The angiotensin AT2 receptor (AT2R) is now regarded as a fully functional and important component of the renin-angiotensin system, with the potential of exerting protective actions in a variety of diseases. This review provides an in-depth view of the AT2R, which has progressed from being an enigma to becoming a therapeutic target.
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Affiliation(s)
- U Muscha Steckelings
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Robert E Widdop
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Edward D Sturrock
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Lizelle Lubbe
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Tahir Hussain
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Elena Kaschina
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Thomas Unger
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Anders Hallberg
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Robert M Carey
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Colin Sumners
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
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6
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Zheng Q, Dong X, Green DP, Dong X. Peripheral mechanisms of chronic pain. MEDICAL REVIEW 2022; 2:251-270. [PMID: 36067122 PMCID: PMC9381002 DOI: 10.1515/mr-2022-0013] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 06/13/2022] [Indexed: 11/15/2022]
Abstract
Abstract
Acutely, pain serves to protect us from potentially harmful stimuli, however damage to the somatosensory system can cause maladaptive changes in neurons leading to chronic pain. Although acute pain is fairly well controlled, chronic pain remains difficult to treat. Chronic pain is primarily a neuropathic condition, but studies examining the mechanisms underlying chronic pain are now looking beyond afferent nerve lesions and exploring new receptor targets, immune cells, and the role of the autonomic nervous system in contributing chronic pain conditions. The studies outlined in this review reveal how chronic pain is not only confined to alterations in the nervous system and presents findings on new treatment targets and for this debilitating disease.
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Affiliation(s)
- Qin Zheng
- Department of Anesthesiology and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Xintong Dong
- The Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Dustin P. Green
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, USA
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Howard Hughes Medical Institute, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
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7
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Gao W, Shen L, Long DD, Pan TT, Wang D, Chai XQ, Hu SS. Angiotensin II type 2 receptor pharmacological agonist, C21, reduces the inflammation and pain hypersensitivity in mice with joint inflammatory pain. Int Immunopharmacol 2022; 110:108921. [PMID: 35724606 DOI: 10.1016/j.intimp.2022.108921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 05/19/2022] [Accepted: 06/01/2022] [Indexed: 11/15/2022]
Abstract
Primary and secondary hyperalgesia develop in response to chronic joint inflammation due to peripheral and central mechanisms. Synovial macrophage and spinal microglia are involved in pain sensitization in arthritis. The level of angiotensin II type 2 receptor (AT2R) is related to the severity of arthritis. This study aimed to determine the role of AT2R in primary and secondary hyperalgesia in joint inflammatory pain in mice. After intra-articular CFA injection, primary hyperalgesia in the ipsilateral knee joint was measured by pressure application meter and gait analysis, secondary hypersensitivity in ipsilateral hind-paw was measured by von-Frey and Hargreaves tests following a combination of global AT2R-deficient (Agtr2-/-) mice and AT2R pharmacological agonist C21. Synovial macrophage and spinal microglia were collected for flow cytometry. Morphological reconstruction of microglia was detected by immunostaining. AT2R expression was investigated by quantitative polymerase chain reaction and western blot. Neuronal hyperactivity was evaluated by c-Fos and CGRP immunostaining. We found that pain hypersensitivity and synovial inflammation in Agtr2-/- mice were significantly exacerbated compared with wild-type mice; conversely, systemically administrated C21 attenuated both of the symptoms. Additionally, spinal microglia were activated, and an abundant increase of spinal AT2R was expressed on activated microglia in response to peripheral joint inflammation. Intrathecally-administrated C21 reversed the secondary hypersensitivity, accompanied by alleviation of spinal microglial activation, spinal neuronal hyperactivity, and calcitonin gene-related peptide content. These findings revealed a beneficial role of AT2R activating stimulation against pain hypersensitivity in joint inflammatory pain via direct modulation of synovial macrophage and spinal microglial activity.
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Affiliation(s)
- Wei Gao
- Anhui Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Liang Shen
- Department of Anesthesiology, Anhui Provincial Hospital Affiliated to Medical University, Hefei 230036, China
| | - Dan-Dan Long
- Department of Anesthesiology, Anhui Provincial Hospital Affiliated to Medical University, Hefei 230036, China
| | - Ting-Ting Pan
- Department of Anesthesiology, Anhui Provincial Hospital Affiliated to Medical University, Hefei 230036, China
| | - Di Wang
- Department of Anesthesiology, Anhui Provincial Hospital Affiliated to Medical University, Hefei 230036, China
| | - Xiao-Qing Chai
- Anhui Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China.
| | - Shan-Shan Hu
- Department of Clinical Laboratory, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, China.
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8
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Wofford KL, Shultz RB, Burrell JC, Cullen DK. Neuroimmune interactions and immunoengineering strategies in peripheral nerve repair. Prog Neurobiol 2022; 208:102172. [PMID: 34492307 PMCID: PMC8712351 DOI: 10.1016/j.pneurobio.2021.102172] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/11/2021] [Accepted: 09/02/2021] [Indexed: 01/03/2023]
Abstract
Peripheral nerve injuries result in disrupted cellular communication between the central nervous system and somatic distal end targets. The peripheral nervous system is capable of independent and extensive regeneration; however, meaningful target muscle reinnervation and functional recovery remain limited and may result in chronic neuropathic pain and diminished quality of life. Macrophages, the primary innate immune cells of the body, are critical contributors to regeneration of the injured peripheral nervous system. However, in some clinical scenarios, macrophages may fail to provide adequate support with optimal timing, duration, and location. Here, we review the history of immunosuppressive and immunomodulatory strategies to treat nerve injuries. Thereafter, we enumerate the ways in which macrophages contribute to successful nerve regeneration. We argue that implementing macrophage-based immunomodulatory therapies is a promising treatment strategy for nerve injuries across a wide range of clinical presentations.
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Affiliation(s)
- Kathryn L Wofford
- Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, 19104, United States; Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, 19104, United States
| | - Robert B Shultz
- Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, 19104, United States; Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, 19104, United States; Axonova Medical, LLC, Philadelphia, PA, 19104, United States
| | - Justin C Burrell
- Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, 19104, United States; Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, 19104, United States; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, United States
| | - D Kacy Cullen
- Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, 19104, United States; Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, 19104, United States; Axonova Medical, LLC, Philadelphia, PA, 19104, United States; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, United States.
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9
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Shedding Light on the Pharmacological Interactions between μ-Opioid Analgesics and Angiotensin Receptor Modulators: A New Option for Treating Chronic Pain. Molecules 2021; 26:molecules26206168. [PMID: 34684749 PMCID: PMC8537077 DOI: 10.3390/molecules26206168] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/05/2021] [Accepted: 10/08/2021] [Indexed: 12/20/2022] Open
Abstract
The current protocols for neuropathic pain management include µ-opioid receptor (MOR) analgesics alongside other drugs; however, there is debate on the effectiveness of opioids. Nevertheless, dose escalation is required to maintain their analgesia, which, in turn, contributes to a further increase in opioid side effects. Finding novel approaches to effectively control chronic pain, particularly neuropathic pain, is a great challenge clinically. Literature data related to pain transmission reveal that angiotensin and its receptors (the AT1R, AT2R, and MAS receptors) could affect the nociception both in the periphery and CNS. The MOR and angiotensin receptors or drugs interacting with these receptors have been independently investigated in relation to analgesia. However, the interaction between the MOR and angiotensin receptors has not been excessively studied in chronic pain, particularly neuropathy. This review aims to shed light on existing literature information in relation to the analgesic action of AT1R and AT2R or MASR ligands in neuropathic pain conditions. Finally, based on literature data, we can hypothesize that combining MOR agonists with AT1R or AT2R antagonists might improve analgesia.
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10
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McCarson KE, Fehrenbacher JC. Models of Inflammation: Carrageenan- or Complete Freund's Adjuvant (CFA)-Induced Edema and Hypersensitivity in the Rat. Curr Protoc 2021; 1:e202. [PMID: 34314105 DOI: 10.1002/cpz1.202] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Animal models of inflammation are used to assess the production of inflammatory mediators at sites of inflammation, the processing of pain sensation at CNS sites, the anti-inflammatory properties of agents such as nonsteroidal anti-inflammatory drugs (NSAIDs), and the efficacy of putative analgesic compounds in reversing cutaneous hypersensitivity. Detailed in this article are methods to elicit and measure carrageenan- and complete Freund's adjuvant (CFA)-induced cutaneous inflammation. Due to possible differences between the dorsal root sensory system and the trigeminal sensory system, injections into either the footpad or vibrissal pad are described. In this manner, cutaneous inflammation can be assessed in tissue innervated by the lumbar dorsal root ganglion neurons (footpad) or by the trigeminal ganglion neurons (vibrissal pad). © 2021 Wiley Periodicals LLC.
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Affiliation(s)
- Kenneth E McCarson
- Kansas Intellectual and Developmental Disabilities Research Center (KIDDRC), Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas
| | - Jill C Fehrenbacher
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana
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11
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Abstract
Growing evidence implicates the renin-angiotensin system (RAS) in multiple facets of neuropathic pain (NP). This narrative review focuses primarily on the major bioactive RAS peptide, Angiotensin II (Ang II), and its receptors, namely type 1 (AT1R) and type 2 (AT2R). Both receptors are involved in the development of NP and represent potential therapeutic targets. We first discuss the potential role of Ang II receptors in modulation of NP in the central nervous system. Ang II receptor expression is widespread in circuits associated with the perception and modulation of pain, but more studies are required to fully characterize receptor distribution, downstream signaling, and therapeutic potential of targeting the central nervous system RAS in NP. We then describe the peripheral neuronal and nonneuronal distribution of the RAS, and its contribution to NP. Other RAS modulators (such as Ang (1-7)) are briefly reviewed as well. AT1R antagonists are analgesic across different pain models, including NP. Several studies show neuronal protection and outgrowth downstream of AT2R activation, which may lead to the use of AT2R agonists in NP. However, blockade of AT2R results in analgesia. Furthermore, expression of the RAS in the immune system and a growing appreciation of neuroimmune crosstalk in NP add another layer of complexity and therapeutic potential of targeting this pathway. A growing number of human studies also hint at the analgesic potential of targeting Ang II signaling. Altogether, Ang II receptor signaling represents a promising, far-reaching, and novel strategy to treat NP.
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12
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The Angiotensin II Type 2 Receptor, a Target for Protection and Regeneration of the Peripheral Nervous System? Pharmaceuticals (Basel) 2021; 14:ph14030175. [PMID: 33668331 PMCID: PMC7996246 DOI: 10.3390/ph14030175] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 02/07/2023] Open
Abstract
Preclinical evidence, accumulated over the past decade, indicates that the angiotensin II type 2 receptor (AT2R) stimulation exerts significant neuroprotective effects in various animal models of neuronal injury, notably in the central nervous system. While the atypical G protein-coupled receptor superfamily nature of AT2R and its related signaling are still under investigation, pharmacological studies have shown that stimulation of AT2R leads to neuritogenesis in vitro and in vivo. In this review, we focus on the potential neuroprotective and neuroregenerative roles of AT2R specifically in the peripheral nervous system (PNS). The first section describes the evidence for AT2R expression in the PNS and highlights current controversies concerning the cellular distribution of the receptor. The second section focuses on AT2R signaling implicated in neuronal survival and in neurite outgrowth. The following sections review the relatively few preclinical studies highlighting the putative neuroprotective and neuroregenerative effects of AT2R stimulation in the context of peripheral neuropathy.
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13
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Suarez-Roca H, Mamoun N, Sigurdson MI, Maixner W. Baroreceptor Modulation of the Cardiovascular System, Pain, Consciousness, and Cognition. Compr Physiol 2021; 11:1373-1423. [PMID: 33577130 DOI: 10.1002/cphy.c190038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Baroreceptors are mechanosensitive elements of the peripheral nervous system that maintain cardiovascular homeostasis by coordinating the responses to external and internal environmental stressors. While it is well known that carotid and cardiopulmonary baroreceptors modulate sympathetic vasomotor and parasympathetic cardiac neural autonomic drive, to avoid excessive fluctuations in vascular tone and maintain intravascular volume, there is increasing recognition that baroreceptors also modulate a wide range of non-cardiovascular physiological responses via projections from the nucleus of the solitary tract to regions of the central nervous system, including the spinal cord. These projections regulate pain perception, sleep, consciousness, and cognition. In this article, we summarize the physiology of baroreceptor pathways and responses to baroreceptor activation with an emphasis on the mechanisms influencing cardiovascular function, pain perception, consciousness, and cognition. Understanding baroreceptor-mediated effects on cardiac and extra-cardiac autonomic activities will further our understanding of the pathophysiology of multiple common clinical conditions, such as chronic pain, disorders of consciousness (e.g., abnormalities in sleep-wake), and cognitive impairment, which may result in the identification and implementation of novel treatment modalities. © 2021 American Physiological Society. Compr Physiol 11:1373-1423, 2021.
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Affiliation(s)
- Heberto Suarez-Roca
- Department of Anesthesiology, Center for Translational Pain Medicine, Duke University, Durham, North Carolina, USA
| | - Negmeldeen Mamoun
- Department of Anesthesiology, Division of Cardiothoracic Anesthesia and Critical Care Medicine, Duke University, Durham, North Carolina, USA
| | - Martin I Sigurdson
- Department of Anesthesiology and Critical Care Medicine, Landspitali, University Hospital, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - William Maixner
- Department of Anesthesiology, Center for Translational Pain Medicine, Duke University, Durham, North Carolina, USA
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14
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Zhang Z, Xu D, Wang J, Cui J, Wu S, Zou L, Shen Y, Jing X, Bai W. Correlated Sensory and Sympathetic Innervation Between the Acupoint BL23 and Kidney in the Rat. Front Integr Neurosci 2021; 14:616778. [PMID: 33505253 PMCID: PMC7829193 DOI: 10.3389/fnint.2020.616778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 12/15/2020] [Indexed: 01/22/2023] Open
Abstract
Objective: To investigate the sensory and sympathetic innervations associated with both acupoint “Shenshu” (BL23) and kidney in the rat for insight into the neuronal correlation between the Back-Shu Point and its corresponding visceral organ. Methods: The BL23 and kidney were selected as the representative acupoint and visceral organ in this study, in which their local nerve fibers were examined by using double fluorescent immunohistochemistry with calcitonin gene-related peptide (CGRP) and tyrosine hydroxylase (TH). Meanwhile, their neuronal correlation in the dorsal root ganglia (DRGs), spinal cord, and sympathetic (paravertebral) chain were investigated using a double fluorescent neural tracing technique with Alexa Fluor 488 and 594 conjugates with cholera toxin subunit B (AF488/594-CTB). Results: The local tissue of acupoint BL23 and the fibrous capsule of kidney distributed abundantly with CGRP- and TH-positive nerve fibers, corresponding to their sensory and sympathetic innervation. On the other hand, the sensory neurons associated with acupoint BL23 and kidney were labeled with AF488/594-CTB and distributed from thoracic (T) 11 to lumbar (L) 3 DRGs and from T10 to L2 DRGs, respectively, in which some of them in T12-T13 DRGs were simultaneously labeled with both AF488/594-CTB. Also, postganglionic neurons associated with both acupoint BL23 and kidney were found in the sympathetic chain at the same spinal segments but separately labeled with AF488-CTB and AF594-CTB. Conclusion: Our study demonstrates the neural characteristics of the acupoint BL23 and kidney in the rat from the perspective of neurochemistry and neural pathways, providing an example for understanding the neuronal correlation between the Back-Shu Points and their corresponding visceral organs. These results suggest that the stimulation of the Back-Shu Points may regulate the activities of the target-organs via the periphery sensory and sympathetic pathways.
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Affiliation(s)
- Zhiyun Zhang
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China.,Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Dongsheng Xu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jia Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jingjing Cui
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Shuang Wu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Ling Zou
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yi Shen
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Xianghong Jing
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China.,Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Wanzhu Bai
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
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15
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Pulakat L, Sumners C. Angiotensin Type 2 Receptors: Painful, or Not? Front Pharmacol 2020; 11:571994. [PMID: 33424587 PMCID: PMC7785813 DOI: 10.3389/fphar.2020.571994] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 11/25/2020] [Indexed: 12/14/2022] Open
Abstract
Pain in response to various types of acute injury can be a protective stimulus to prevent the organism from using the injured part and allow tissue repair and healing. On the other hand, neuropathic pain, defined as ‘pain caused by a lesion or disease of the somatosensory nervous system’, is a debilitating pathology. The TRPA1 neurons in the Dorsal Root Ganglion (DRG) respond to reactive oxygen species (ROS) and induce pain. In acute nerve injury and inflammation, macrophages infiltrating the site of injury undergo an oxidative burst, and generate ROS that promote tissue repair and induce pain via TRPA1. The latter discourages using the injured limb, with a lack of movement helping wound healing. In chronic inflammation caused by diabetes, cancer etc., ROS levels increase systemically and modulate TRPA1 neuronal functions and cause debilitating neuropathic pain. It is important to distinguish between drug targets that elicit protective vs. debilitating pain when developing effective drugs for neuropathic pain. In this context, the connection of the Angiotensin type 2 receptor (AT2R) to neuropathic pain presents an interesting dilemma. Several lines of evidence show that AT2R activation promotes anti-inflammatory and anti-nociceptive signaling, tissue repair, and suppresses ROS in chronic inflammatory models. Conversely, some studies suggest that AT2R antagonists are anti-nociceptive and therefore AT2R is a drug target for neuropathic pain. However, AT2R expression in nociceptive neurons is lacking, indicating that neuronal AT2R is not involved in neuropathic pain. It is also important to consider that Novartis terminated their phase II clinical trial (EMPHENE) to validate that AT2R antagonist EMA401 mitigates post-herpetic neuralgia. This trial, conducted in Australia, United Kingdom, and a number of European and Asian countries in 2019, was discontinued due to pre-clinical drug toxicity data. Moreover, early data from the trial did not show statistically significant positive outcomes. These facts suggest that may AT2R not be the proper drug target for neuropathic pain in humans and its inhibition can be harmful.
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Affiliation(s)
- Lakshmi Pulakat
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA, United States.,Department of Medicine, Tufts University School of Medicine, Boston, MA, United States
| | - Colin Sumners
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL, United States
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16
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Szczepanska-Sadowska E, Cudnoch-Jedrzejewska A, Sadowski B. Differential role of specific cardiovascular neuropeptides in pain regulation: Relevance to cardiovascular diseases. Neuropeptides 2020; 81:102046. [PMID: 32284215 DOI: 10.1016/j.npep.2020.102046] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 03/27/2020] [Accepted: 03/29/2020] [Indexed: 12/11/2022]
Abstract
In many instances, the perception of pain is disproportionate to the strength of the algesic stimulus. Excessive or inadequate pain sensation is frequently observed in cardiovascular diseases, especially in coronary ischemia. The mechanisms responsible for individual differences in the perception of cardiovascular pain are not well recognized. Cardiovascular disorders may provoke pain in multiple ways engaging molecules released locally in the heart due to tissue ischemia, inflammation or cellular stress, and through neurogenic and endocrine mechanisms brought into action by hemodynamic disturbances. Cardiovascular neuropeptides, namely angiotensin II (Ang II), angiotensin-(1-7) [Ang-(1-7)], vasopressin, oxytocin, and orexins belong to this group. Although participation of these peptides in the regulation of circulation and pain has been firmly established, their mutual interaction in the regulation of pain in cardiovascular diseases has not been profoundly analyzed. In the present review we discuss the regulation of the release, and mechanisms of the central and systemic actions of these peptides on the cardiovascular system in the context of their central and peripheral nociceptive (Ang II) and antinociceptive [Ang-(1-7), vasopressin, oxytocin, orexins] properties. We also consider the possibility that they may play a significant role in the modulation of pain in cardiovascular diseases. The rationale for focusing attention on these very compounds was based on the following premises (1) cardiovascular disturbances influence the release of these peptides (2) they regulate vascular tone and cardiac function and can influence the intensity of ischemia - the factor initiating pain signals in the cardiovascular system, (3) they differentially modulate nociception through peripheral and central mechanisms, and their effect strongly depends on specific receptors and site of action. Accordingly, an altered release of these peptides and/or pharmacological blockade of their receptors may have a significant but different impact on individual sensation of pain and comfort of an individual patient.
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Affiliation(s)
- Ewa Szczepanska-Sadowska
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Banacha 1b, Warsaw, Poland.
| | - Agnieszka Cudnoch-Jedrzejewska
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Banacha 1b, Warsaw, Poland
| | - Bogdan Sadowski
- School of Engineering and Health, Bitwy Warszawskiej 1920 r. 18, Warsaw, Poland
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17
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Oga S, Goto K, Sakamoto J, Honda Y, Sasaki R, Ishikawa K, Kataoka H, Nakano J, Origuchi T, Okita M. Mechanisms underlying immobilization-induced muscle pain in rats. Muscle Nerve 2020; 61:662-670. [PMID: 32083755 DOI: 10.1002/mus.26840] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 12/01/2019] [Accepted: 12/03/2019] [Indexed: 12/27/2022]
Abstract
INTRODUCTION We investigated the mechanisms underlying immobilization-induced muscle pain in rats. METHODS In rat skeletal muscle, pressure pain threshold (PPT) of the gastrocnemius muscle was measured, and nerve growth factor (NGF) level, peripheral nerve fiber density, macrophage number, and interleukin-1β (IL-1β) mRNA expression were examined. An NGF receptor inhibitor was injected intramuscularly to assess the relationship between PPT and NGF levels. RESULTS Immobilization resulted in a decrease in PPT and increases in NGF level, C-fiber density, M1 macrophage number, and IL-1β mRNA expression. Injection of NGF receptor inhibitor reversed the decrease in PPT. DISCUSSION NGF upregulation may be a major contributor to immobilization-induced muscle pain. The increases in C-fiber density, M1 macrophage number, and IL-1β mRNA expression may be related to immobilization-induced muscle pain.
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Affiliation(s)
- Satoshi Oga
- Department of Locomotive Rehabilitation Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.,Department of Rehabilitation, Japanese Red Cross Nagasaki Genbaku Hospital, Nagasaki, Japan
| | - Kyo Goto
- Department of Rehabilitation, Nagasaki Memorial Hospital, Nagasaki, Japan
| | - Junya Sakamoto
- Department of Physical Therapy Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Yuichiro Honda
- Department of Rehabilitation, Nagasaki University Hospital, Nagasaki, Japan
| | - Ryo Sasaki
- Department of Locomotive Rehabilitation Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.,Department of Rehabilitation, Juzenkai Hospital, Nagasaki, Japan
| | - Kumiko Ishikawa
- Department of Rehabilitation, Nagasaki University Hospital, Nagasaki, Japan
| | - Hideki Kataoka
- Department of Rehabilitation, Nagasaki Memorial Hospital, Nagasaki, Japan
| | - Jiro Nakano
- Department of Physical Therapy Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Tomoki Origuchi
- Department of Locomotive Rehabilitation Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Minoru Okita
- Department of Locomotive Rehabilitation Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
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18
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Benitez SG, Seltzer AM, Messina DN, Foscolo MR, Patterson SI, Acosta CG. Cutaneous inflammation differentially regulates the expression and function of Angiotensin-II types 1 and 2 receptors in rat primary sensory neurons. J Neurochem 2019; 152:675-696. [PMID: 31386177 DOI: 10.1111/jnc.14848] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 06/25/2019] [Accepted: 07/31/2019] [Indexed: 12/14/2022]
Abstract
Neuropathic and inflammatory pain results from cellular and molecular changes in dorsal root ganglion (DRG) neurons. The type-2 receptor for Angiotensin-II (AT2R) has been involved in this type of pain. However, the underlying mechanisms are poorly understood, including the role of the type-1 receptor for Angiotensin-II (AT1R). Here, we used a combination of immunohistochemistry and immunocytochemistry, RT-PCR and in vitro and in vivo pharmacological manipulation to examine how cutaneous inflammation affected the expression of AT1R and AT2R in subpopulations of rat DRG neurons and studied their impact on inflammation-induced neuritogenesis. We demonstrated that AT2R-neurons express C- or A-neuron markers, primarily IB4, trkA, and substance-P. AT1R expression was highest in small neurons and co-localized significantly with AT2R. In vitro, an inflammatory soup caused significant elevation of AT2R mRNA, whereas AT1R mRNA levels remained unchanged. In vivo, we found a unique pattern of change in the expression of AT1R and AT2R after cutaneous inflammation. AT2R increased in small neurons at 1 day and in medium size neurons at 4 days. Interestingly, cutaneous inflammation increased AT1R levels only in large neurons at 4 days. We found that in vitro and in vivo AT1R and AT2R acted co-operatively to regulate DRG neurite outgrowth. In vivo, AT2R inhibition impacted more on non-peptidergic C-neurons neuritogenesis, whereas AT1R blockade affected primarily peptidergic nerve terminals. Thus, cutaneous-induced inflammation regulated AT1R and AT2R expression and function in different DRG neuronal subpopulations at different times. These findings must be considered when targeting AT1R and AT2R to treat chronic inflammatory pain. Cover Image for this issue: doi: 10.1111/jnc.14737.
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Affiliation(s)
- Sergio G Benitez
- Laboratorio de Neurobiología del Dolor, Instituto de Histología y Embriología de Mendoza (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Alicia M Seltzer
- Laboratorio de Neurobiología, Instituto de Embriología e Histología (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Diego N Messina
- Laboratorio de Neurobiología del Dolor, Instituto de Histología y Embriología de Mendoza (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Mabel R Foscolo
- Laboratorio de Neurobiología del Dolor, Instituto de Histología y Embriología de Mendoza (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Sean I Patterson
- Departamento de Morfofisiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.,Instituto de Histología y Embriología - CONICET, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Cristian G Acosta
- Laboratorio de Neurobiología del Dolor, Instituto de Histología y Embriología de Mendoza (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
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19
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Barry CM, Matusica D, Haberberger RV. Emerging Evidence of Macrophage Contribution to Hyperinnervation and Nociceptor Sensitization in Vulvodynia. Front Mol Neurosci 2019; 12:186. [PMID: 31447644 PMCID: PMC6691023 DOI: 10.3389/fnmol.2019.00186] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 07/19/2019] [Indexed: 12/16/2022] Open
Abstract
Vulvodynia is an idiopathic chronic pain disorder and a leading cause of dyspareunia, or pain associated with sexual intercourse, for women. The key pathophysiological features of vulvodynia are vaginal hyperinnervation and nociceptor sensitization. These features have been described consistently by research groups over the past 30 years, but currently there is no first-line recommended treatment that targets this pathophysiology. Instead, psychological interventions, pelvic floor physiotherapy and surgery to remove painful tissue are recommended, as these are the few interventions that have shown some benefit in clinical trials. Recurrence of vulvodynia is frequent, even after vestibulectomy and questions regarding etiology remain. Vestibular biopsies from women with vulvodynia contain increased abundance of immune cells including macrophages as well as increased numbers of nerve fibers. Macrophages have multiple roles in the induction and resolution of inflammation and their function can be broadly described as pro-inflammatory or anti-inflammatory depending on their polarization state. This state is not fixed and can alter rapidly in response to the microenvironment. Essentially, M1, or classically activated macrophages, produce pro-inflammatory cytokines and promote nociceptor sensitization and mechanical allodynia, whereas M2, or alternatively activated macrophages produce anti-inflammatory cytokines and promote functions such as wound healing. Signaling between macrophages and neurons has been shown to promote axonal sprouting and nociceptor sensitization. This mini review considers emerging evidence that macrophages may play a role in nociceptor sensitization and hyperinnervation relevant to vulvodynia and considers the implications for development of new therapeutic strategies.
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Affiliation(s)
- Christine Mary Barry
- Musculoskeletal Neurobiology Laboratory, Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Dusan Matusica
- Pain and Pulmonary Neurobiology Laboratory, Centre for Neuroscience, Órama Institute, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Rainer Viktor Haberberger
- Pain and Pulmonary Neurobiology Laboratory, Centre for Neuroscience, Órama Institute, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
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20
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Abstract
Peripheral nerve damage initiates a complex series of structural and cellular processes that culminate in chronic neuropathic pain. The recent success of a type 2 angiotensin II (Ang II) receptor (AT2R) antagonist in a phase II clinical trial for the treatment of postherpetic neuralgia suggests angiotensin signaling is involved in neuropathic pain. However, transcriptome analysis indicates a lack of AT2R gene (Agtr2) expression in human and rodent sensory ganglia, raising questions regarding the tissue/cell target underlying the analgesic effect of AT2R antagonism. We show that selective antagonism of AT2R attenuates neuropathic but not inflammatory mechanical and cold pain hypersensitivity behaviors in mice. Agtr2-expressing macrophages (MΦs) constitute the predominant immune cells that infiltrate the site of nerve injury. Interestingly, neuropathic mechanical and cold pain hypersensitivity can be attenuated by chemogenetic depletion of peripheral MΦs and AT2R-null hematopoietic cell transplantation. Our study identifies AT2R on peripheral MΦs as a critical trigger for pain sensitization at the site of nerve injury, and therefore proposes a translatable peripheral mechanism underlying chronic neuropathic pain.
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Angiotensin II Triggers Peripheral Macrophage-to-Sensory Neuron Redox Crosstalk to Elicit Pain. J Neurosci 2018; 38:7032-7057. [PMID: 29976627 DOI: 10.1523/jneurosci.3542-17.2018] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 05/03/2018] [Accepted: 05/07/2018] [Indexed: 12/20/2022] Open
Abstract
Injury, inflammation, and nerve damage initiate a wide variety of cellular and molecular processes that culminate in hyperexcitation of sensory nerves, which underlies chronic inflammatory and neuropathic pain. Using behavioral readouts of pain hypersensitivity induced by angiotensin II (Ang II) injection into mouse hindpaws, our study shows that activation of the type 2 Ang II receptor (AT2R) and the cell-damage-sensing ion channel TRPA1 are required for peripheral mechanical pain sensitization induced by Ang II in male and female mice. However, we show that AT2R is not expressed in mouse and human dorsal root ganglia (DRG) sensory neurons. Instead, expression/activation of AT2R on peripheral/skin macrophages (MΦs) constitutes a critical trigger of mouse and human DRG sensory neuron excitation. Ang II-induced peripheral mechanical pain hypersensitivity can be attenuated by chemogenetic depletion of peripheral MΦs. Furthermore, AT2R activation in MΦs triggers production of reactive oxygen/nitrogen species, which trans-activate TRPA1 on mouse and human DRG sensory neurons via cysteine modification of the channel. Our study thus identifies a translatable immune cell-to-sensory neuron signaling crosstalk underlying peripheral nociceptor sensitization. This form of cell-to-cell signaling represents a critical peripheral mechanism for chronic pain and thus identifies multiple druggable analgesic targets.SIGNIFICANCE STATEMENT Pain is a widespread health problem that is undermanaged by currently available analgesics. Findings from a recent clinical trial on a type II angiotensin II receptor (AT2R) antagonist showed effective analgesia for neuropathic pain. AT2R antagonists have been shown to reduce neuropathy-, inflammation- and bone cancer-associated pain in rodents. We report that activation of AT2R in macrophages (MΦs) that infiltrate the site of injury, but not in sensory neurons, triggers an intercellular redox communication with sensory neurons via activation of the cell damage/pain-sensing ion channel TRPA1. This MΦ-to-sensory neuron crosstalk results in peripheral pain sensitization. Our findings provide an evidence-based mechanism underlying the analgesic action of AT2R antagonists, which could accelerate the development of efficacious non-opioid analgesic drugs for multiple pain conditions.
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Sharma H, Ji E, Yap P, Vilimas P, Kyloh M, Spencer NJ, Haberberger RV, Barry CM. Innervation Changes Induced by Inflammation in the Murine Vagina. Neuroscience 2018; 372:16-26. [DOI: 10.1016/j.neuroscience.2017.12.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 12/15/2017] [Accepted: 12/19/2017] [Indexed: 12/28/2022]
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Chakrabarty A, Liao Z, Mu Y, Smith PG. Inflammatory Renin-Angiotensin System Disruption Attenuates Sensory Hyperinnervation and Mechanical Hypersensitivity in a Rat Model of Provoked Vestibulodynia. THE JOURNAL OF PAIN 2017; 19:264-277. [PMID: 29155208 DOI: 10.1016/j.jpain.2017.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 10/25/2017] [Accepted: 10/30/2017] [Indexed: 12/20/2022]
Abstract
Vestibulodynia is characterized by perivaginal mechanical hypersensitivity, hyperinnervation, and abundant inflammatory cells expressing renin-angiotensin system proteins. We developed a tractable rat model of vestibulodynia to further assess the contributions of the renin-angiotensin system. Complete Freund's adjuvant injected into the posterior vestibule induced marked vestibular hypersensitivity throughout a 7-day test period. Numbers of axons immunoreactive for PGP9.5, calcitonin gene-related peptide, and GFRα2 were increased. Numbers of macrophages and T cells were also increased whereas B cells were not. Renin-angiotensin-associated proteins were abundant, with T cells as well as macrophages contributing to increased renin and angiotensinogen. Media conditioned with inflamed vestibular tissue promoted neurite sprouting by rat dorsal root ganglion neurons in vitro, and this was blocked by the angiotensin II receptor type 2 receptor antagonist PD123319 or by an angiotensin II function blocking antibody. Sensory axon sprouting induced by inflamed tissue was dependent on activity of angiotensin-converting enzyme or chymase, but not cathepsin G. Thus, vestibular Complete Freund's adjuvant injection substantially recapitulates changes seen in patients with provoked vestibulodynia, and shows that manipulation of the local inflammatory renin-angiotensin system may be a useful therapeutic strategy. PERSPECTIVE This study provides evidence that inflammation of the rat vestibule induces a phenotype recapitulating behavioral and cytological features of human vestibulodynia. The model confirms a crucial role of the local inflammatory renin-angiotensin system in hypersensitivity and hyperinnervation. Targeting this system holds promise for developing new nonopioid analgesic treatment strategies.
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Affiliation(s)
- Anuradha Chakrabarty
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Zhaohui Liao
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Ying Mu
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Peter G Smith
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas.
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Neuronal cytoskeletal gene dysregulation and mechanical hypersensitivity in a rat model of Rett syndrome. Proc Natl Acad Sci U S A 2017; 114:E6952-E6961. [PMID: 28760966 DOI: 10.1073/pnas.1618210114] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Children with Rett syndrome show abnormal cutaneous sensitivity. The precise nature of sensory abnormalities and underlying molecular mechanisms remain largely unknown. Rats with methyl-CpG binding protein 2 (MeCP2) mutation, characteristic of Rett syndrome, show hypersensitivity to pressure and cold, but hyposensitivity to heat. They also show cutaneous hyperinnervation by nonpeptidergic sensory axons, which include subpopulations encoding noxious mechanical and cold stimuli, whereas peptidergic thermosensory innervation is reduced. MeCP2 knockdown confined to dorsal root ganglion sensory neurons replicated this phenotype in vivo, and cultured MeCP2-deficient ganglion neurons showed augmented axonogenesis. Transcriptome analysis revealed dysregulation of genes associated with cytoskeletal dynamics, particularly those controlling actin polymerization and focal-adhesion formation necessary for axon growth and mechanosensory transduction. Down-regulation of these genes by topoisomerase inhibition prevented abnormal axon sprouting. We identified eight key affected genes controlling actin signaling and adhesion formation, including members of the Arhgap, Tiam, and cadherin families. Simultaneous virally mediated knockdown of these genes in Rett rats prevented sensory hyperinnervation and reversed mechanical hypersensitivity, indicating a causal role in abnormal outgrowth and sensitivity. Thus, MeCP2 regulates ganglion neuronal genes controlling cytoskeletal dynamics, which in turn determines axon outgrowth and mechanosensory function and may contribute to altered pain sensitivity in Rett syndrome.
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Liao Z, Chakrabarty A, Mu Y, Bhattacherjee A, Goestch M, Leclair CM, Smith PG. A Local Inflammatory Renin-Angiotensin System Drives Sensory Axon Sprouting in Provoked Vestibulodynia. THE JOURNAL OF PAIN 2017; 18:511-525. [PMID: 28062309 PMCID: PMC6261484 DOI: 10.1016/j.jpain.2016.12.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 12/01/2016] [Accepted: 12/12/2016] [Indexed: 12/24/2022]
Abstract
Vestibulodynia is a form of provoked vulvodynia characterized by profound tenderness, hyperinnervation, and frequently inflammation within well-defined areas of the human vestibule. Previous experiments in animal models show that inflammatory hypersensitivity and hyperinnervation occur in concert with establishment of a local renin-angiotensin system (RAS). Moreover, mechanical hypersensitivity and sensory axon sprouting are prevented by blocking effects of angiotensin II on angiotensin II receptor type 2 (AT2) receptors. This case-control study assessed whether a RAS contributes to hyperinnervation observed in human vestibulodynia. Vestibular biopsies from asymptomatic controls or patients' nontender areas showed moderate innervation and small numbers of inflammatory cells. In women with vestibulodynia, tender areas contained increased numbers of mechanoreceptive nociceptor axons, T-cells, macrophages, and B-cells, whereas mast cells were unchanged. RAS proteins were increased because of greater numbers of T cells and B cells expressing angiotensinogen, and increased renin-expressing T cells and macrophages. Chymase, which converts angiotensin I to angiotensin II, was present in constant numbers of mast cells. To determine if tender vestibular tissue generates angiotensin II that promotes axon sprouting, we conditioned culture medium with vestibular tissue. Rat sensory neurons cultured in control-conditioned medium showed normal axon outgrowth, whereas those in tender tissue-conditioned medium showed enhanced sprouting that was prevented by adding an AT2 antagonist or angiotensin II neutralizing antibody. Hypersensitivity in provoked vestibulodynia is therefore characterized by abnormal mechanonociceptor axon proliferation, which is attributable to inflammatory cell-derived angiotensin II (or a closely related peptide) acting on neuronal AT2 receptors. Accordingly, reducing inflammation or blocking AT2 represent rational strategies to mitigate this common pain syndrome. PERSPECTIVE This study provides evidence that local inflammation leads to angiotensin II formation, which acts on the AT2 to induce nociceptor axon sprouting in vulvodynia. Preventing inflammation and blocking AT2 therefore present potential pharmacological strategies for reducing vestibular pain.
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Affiliation(s)
- Zhaohui Liao
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Anuradha Chakrabarty
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Ying Mu
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Aritra Bhattacherjee
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Martha Goestch
- Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon
| | - Catherine M Leclair
- Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon
| | - Peter G Smith
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas.
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Benitez S, Seltzer A, Acosta C. Nociceptor-like rat dorsal root ganglion neurons express the angiotensin-II AT2 receptor throughout development. Int J Dev Neurosci 2016; 56:10-17. [PMID: 27825832 DOI: 10.1016/j.ijdevneu.2016.11.001] [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: 10/17/2016] [Revised: 10/31/2016] [Accepted: 11/01/2016] [Indexed: 01/06/2023] Open
Abstract
AT2 receptor (AT2R) plays a functional role in foetal development. Its expression declines in most tissues soon after birth but stays high in sensory areas of the adult nervous system. In the dorsal root ganglia (DRG) the expression pattern of AT2R during development and the identity of the subpopulation expressing it remain unknown. Using a combination of semi-quantitative PCR, western blotting and immunohistochemistry we examined the expression of AT2R at mRNA and protein levels in rat DRGs from embryonic day 15 (E15) until postnatal day 30 (PN30). We found that both AT2R mRNA and protein levels exhibited only minor (statistically non-significant) fluctuations from E15 to PN30. Detailed quantitative analysis of ABC/DAB AT2R staining showed a) that the receptor was present in most neurons at E15 and E18 and b) that postnatally it was predominantly expressed by small DRG neurons. Given that small neurons are putative C-nociceptors and the proposed role of AT2R in neuropathic pain, we next examined whether these AT2R-positive neurons co-localized with Ret and trkA embryonically and with IB4-binding postnatally. Most AT2R-positive neurons expressed trkA embryonically and bound IB4 postnatally. We found strong positive statistically highly significant correlations between AT2R cytoplasmic%intensities and trkA at E15/E18 and with Ret only at E18. Cytoplasmic AT2R also strongly and positively correlated with IB4-binding at PN3, 15 and 30. Our demonstration that a subpopulation of C-nociceptor-like neurons expresses AT2R during development supports a role for this receptor in neuropathic pain.
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Affiliation(s)
- Sergio Benitez
- Instituto de Histología y Embriología de Mendoza (IHEM), Facultad de Ciencias Medicas, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
| | - Alicia Seltzer
- Instituto de Histología y Embriología de Mendoza (IHEM), Facultad de Ciencias Medicas, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
| | - Cristian Acosta
- Instituto de Histología y Embriología de Mendoza (IHEM), Facultad de Ciencias Medicas, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina.
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Norman BH, McDermott JS. Targeting the Nerve Growth Factor (NGF) Pathway in Drug Discovery. Potential Applications to New Therapies for Chronic Pain. J Med Chem 2016; 60:66-88. [DOI: 10.1021/acs.jmedchem.6b00964] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Bryan H. Norman
- Discovery Chemistry
Research and Technologies and ‡Neurophysiology, Lilly Research Laboratories, A Division of Eli Lilly and Company, Indianapolis, Lilly
Corporate Center, Indiana 46285, United States
| | - Jeff S. McDermott
- Discovery Chemistry
Research and Technologies and ‡Neurophysiology, Lilly Research Laboratories, A Division of Eli Lilly and Company, Indianapolis, Lilly
Corporate Center, Indiana 46285, United States
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Selective small molecule angiotensin II type 2 receptor antagonists for neuropathic pain: preclinical and clinical studies. Pain 2016; 157 Suppl 1:S33-S41. [PMID: 26785154 DOI: 10.1097/j.pain.0000000000000369] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Neuropathic pain affects up to 10% of the general population, but drug treatments recommended for the treatment of neuropathic pain are associated with modest efficacy and/or produce dose-limiting side effects. Hence, neuropathic pain is an unmet medical need. In the past 2 decades, research on the pathobiology of neuropathic pain has revealed many novel pain targets for use in analgesic drug discovery programs. However, these efforts have been largely unsuccessful as molecules that showed promising pain relief in rodent models of neuropathic pain generally failed to produce analgesia in early phase clinical trials in patients with neuropathic pain. One notable exception is the angiotensin II type 2 (AT2) receptor that has clinical validity on the basis of a successful double-blind, randomized, placebo-controlled, clinical trial of EMA401, a highly selective, orally active, peripherally restricted AT2 receptor antagonist in patients with postherpetic neuralgia. In this study, we review research to date on target validation, efficacy, and mode of action of small molecule AT2 receptor antagonists in rodent models of peripheral neuropathic pain and in cultured human sensory neurons, the preclinical pharmacokinetics of these compounds, and the outcome of the above clinical trial.
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29
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Bessaguet F, Magy L, Desmoulière A, Demiot C. The therapeutic potential of renin angiotensin aldosterone system (RAAS) in chronic pain: from preclinical studies to clinical trials. Expert Rev Neurother 2016; 16:331-9. [DOI: 10.1586/14737175.2016.1150179] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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30
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Araiza-Saldaña CI, Pedraza-Priego EF, Torres-López JE, Rocha-González HI, Castañeda-Corral G, Hong-Chong E, Granados-Soto V. Fosinopril Prevents the Development of Tactile Allodynia in a Streptozotocin-Induced Diabetic Rat Model. Drug Dev Res 2015; 76:442-9. [DOI: 10.1002/ddr.21280] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 08/22/2015] [Indexed: 01/01/2023]
Affiliation(s)
| | - Erick Fabián Pedraza-Priego
- División Académica de Ciencias de la Salud; Universidad Juárez Autónoma de Tabasco; Villahermosa Tabasco Mexico
| | - Jorge Elías Torres-López
- División Académica de Ciencias de la Salud; Universidad Juárez Autónoma de Tabasco; Villahermosa Tabasco Mexico
| | - Héctor Isaac Rocha-González
- Sección de Estudios de Posgrado e Investigación; Escuela Superior de Medicina, Instituto Politécnico Nacional; México D.F. Mexico
| | | | - Enrique Hong-Chong
- Departamento de Farmacobiología; Centro de Investigación y de Estudios Avanzados (Cinvestav), Sede Sur.; México D.F. Mexico
| | - Vinicio Granados-Soto
- Departamento de Farmacobiología; Centro de Investigación y de Estudios Avanzados (Cinvestav), Sede Sur.; México D.F. Mexico
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31
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Goetsch MF, Lim JY, Caughey AB. A Practical Solution for Dyspareunia in Breast Cancer Survivors: A Randomized Controlled Trial. J Clin Oncol 2015. [PMID: 26215946 DOI: 10.1200/jco.2014.60.7366] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE Dyspareunia is common in breast cancer survivors because of low estrogen. This study explored whether dyspareunia is introital pain, preventable with analgesic liquid. PATIENTS AND METHODS In a randomized, controlled, double-blind trial, estrogen-deficient breast cancer survivors with severe penetrative dyspareunia applied either saline or 4% aqueous lidocaine to the vulvar vestibule for 3 minutes before vaginal penetration. After a 1-month blinded trial of patient-assessed twice-per-week tampon insertion or intercourse, all patients received lidocaine for 2 months in an open-label trial. The primary outcome was patient-related assessment of penetration pain on a scale of zero to 10. Secondary outcomes were sexual distress (Female Sexual Distress Scale), sexual function (Sexual Function Questionnaire), and resumption of intercourse. Comparisons were made with the Mann-Whitney U and Wilcoxon signed rank test with significance set at P < .05. RESULTS In all, 46 patients, screened to exclude those with pelvic muscle and organ pain, uniformly had clinical evidence of severe vulvovaginal atrophy, dyspareunia (median pain score, 8 of 10; interquartile range [IQR], 7 to 9), increased sexual distress scores (median, 30.5; IQR, 23 to 37; abnormal, > 11), and abnormal sexual function. Users of lidocaine reported less pain during intercourse in the blinded phase (median score of 1.0 compared with saline score of 5.3; P = .007). After open-label lidocaine use, 37 (90%) of 41 reported comfortable penetration. Sexual distress decreased (median score, 14; IQR, 3 to 20; P < .001), and sexual function improved in all but one domain. Of 20 prior abstainers from intercourse who completed the study, 17 (85%) had resumed comfortable penetrative intimacy. No partners reported penile numbness. CONCLUSION Breast cancer survivors with menopausal dyspareunia can have comfortable intercourse after applying liquid lidocaine compresses to the vulvar vestibule before penetration.
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Affiliation(s)
| | - Jeong Y Lim
- All authors: Oregon Health & Science University, Portland, OR
| | - Aaron B Caughey
- All authors: Oregon Health & Science University, Portland, OR
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Anand U, Yiangou Y, Sinisi M, Fox M, MacQuillan A, Quick T, Korchev YE, Bountra C, McCarthy T, Anand P. Mechanisms underlying clinical efficacy of Angiotensin II type 2 receptor (AT2R) antagonist EMA401 in neuropathic pain: clinical tissue and in vitro studies. Mol Pain 2015; 11:38. [PMID: 26111701 PMCID: PMC4482278 DOI: 10.1186/s12990-015-0038-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 06/11/2015] [Indexed: 12/20/2022] Open
Abstract
Background The clinical efficacy of the Angiotensin II (AngII) receptor AT2R antagonist EMA401, a novel peripherally-restricted analgesic, was reported recently in post-herpetic neuralgia. While previous studies have shown that AT2R is expressed by nociceptors in human DRG (hDRG), and that EMA401 inhibits capsaicin responses in cultured hDRG neurons, the expression and levels of its endogenous ligands AngII and AngIII in clinical neuropathic pain tissues, and their signalling pathways, require investigation. We have immunostained AngII, AT2R and the capsaicin receptor TRPV1 in control post-mortem and avulsion injured hDRG, control and injured human nerves, and in cultured hDRG neurons. AngII, AngIII, and Ang-(1-7) levels were quantified by ELISA. The in vitro effects of AngII, AT2R agonist C21, and Nerve growth factor (NGF) were measured on neurite lengths; AngII, NGF and EMA401 effects on expression of p38 and p42/44 MAPK were measured using quantitative immunofluorescence, and on capsaicin responses using calcium imaging. Results AngII immunostaining was observed in approximately 75% of small/medium diameter neurons in control (n = 5) and avulsion injured (n = 8) hDRG, but not large neurons i.e. similar to TRPV1. AngII was co-localised with AT2R and TRPV1 in hDRG and in vitro. AngII staining by image analysis showed no significant difference between control (n = 12) and injured (n = 13) human nerves. AngII levels by ELISA were also similar in control human nerves (4.09 ± 0.36 pmol/g, n = 31), injured nerves (3.99 ± 0.79 pmol/g, n = 7), and painful neuromas (3.43 ± 0.73 pmol/g, n = 12); AngIII and Ang-(1-7) levels were undetectable (<0.03 and 0.05 pmol/g respectively). Neurite lengths were significantly increased in the presence of NGF, AngII and C21 in cultured DRG neurons. AngII and, as expected, NGF significantly increased signal intensity of p38 and p42/44 MAPK, which was reversed by EMA401. AngII mediated sensitization of capsaicin responses was not observed in the presence of MAP kinase inhibitor PD98059, and the kinase inhibitor staurosporine. Conclusion The major AT2R ligand in human peripheral nerves is AngII, and its levels are maintained in injured nerves. EMA401 may act on paracrine/autocrine mechanisms at peripheral nerve terminals, or intracrine mechanisms, to reduce neuropathic pain signalling in AngII/NGF/TRPV1-convergent pathways.
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Affiliation(s)
- Uma Anand
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College London, Area A, Ground Floor, Du Cane Rd, London, W12 ONN, UK. .,Nanomedicine Research Laboratory, Division of Medicine, Hammersmith Hospital, Imperial College London, BN5 Commonwealth Building, London, W12 0NN, UK.
| | - Yiangos Yiangou
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College London, Area A, Ground Floor, Du Cane Rd, London, W12 ONN, UK.
| | - Marco Sinisi
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College London, Area A, Ground Floor, Du Cane Rd, London, W12 ONN, UK. .,Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Stanmore, Middlesex, HA7 4LP, UK.
| | - Michael Fox
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College London, Area A, Ground Floor, Du Cane Rd, London, W12 ONN, UK. .,Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Stanmore, Middlesex, HA7 4LP, UK.
| | - Anthony MacQuillan
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College London, Area A, Ground Floor, Du Cane Rd, London, W12 ONN, UK. .,Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Stanmore, Middlesex, HA7 4LP, UK.
| | - Tom Quick
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College London, Area A, Ground Floor, Du Cane Rd, London, W12 ONN, UK. .,Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Stanmore, Middlesex, HA7 4LP, UK.
| | - Yuri E Korchev
- Nanomedicine Research Laboratory, Division of Medicine, Hammersmith Hospital, Imperial College London, BN5 Commonwealth Building, London, W12 0NN, UK.
| | - Chas Bountra
- University of Oxford Structural Genomics Consortium, Old Road, Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK.
| | - Tom McCarthy
- Spinifex Pharmaceuticals Pty Ltd, Corporate One, Suite G5, 84 Hotham St, Preston, VIC, 3072, Australia.
| | - Praveen Anand
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College London, Area A, Ground Floor, Du Cane Rd, London, W12 ONN, UK.
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Liao Z, Smith PG. Persistent genital hyperinnervation following progesterone administration to adolescent female rats. Biol Reprod 2014; 91:144. [PMID: 25359899 DOI: 10.1095/biolreprod.114.121103] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Provoked vestibulodynia, a female pelvic pain syndrome affecting substantial numbers of women, is characterized by genital hypersensitivity and sensory hyperinnervation. Previous studies have shown that the risk of developing provoked vestibulodynia is markedly elevated following adolescent use of oral contraceptives with high progesterone content. We hypothesized that progesterone, a steroid hormone with known neurotropic properties, may alter genital innervation through direct or indirect actions. Female Sprague Dawley rats received progesterone (20 mg/kg subcutaneously) from Days 20-27; tissue was removed for analysis in some rats on Day 28, while others were ovariectomized on Day 43 and infused for 7 days with vehicle or 17beta estradiol. Progesterone resulted in overall increases in vaginal innervation at both Day 28 and 50 due to proliferation of peptidergic sensory and sympathetic (but not parasympathetic) axons. Estradiol reduced innervation in progesterone-treated and untreated groups. To assess the mechanisms of sensory hyperinnervation, we cultured dissociated dorsal root ganglion neurons and found that progesterone increases neurite outgrowth by small unmyelinated (but not myelinated) sensory neurons, it was receptor mediated, and it was nonadditive with NGF. Pretreatment of ganglion with progesterone also increased neurite outgrowth in response to vaginal target explants. However, pretreatment of vaginal target with progesterone did not improve outgrowth. We conclude that adolescent progesterone exposure may contribute to provoked vestibulodynia by eliciting persistent genital hyperinnervation via a direct effect on unmyelinated sensory nociceptor neurons and that estradiol, a well-documented therapeutic, may alleviate symptoms in part by reducing progesterone-induced sensory hyperinnervation.
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Affiliation(s)
- Zhaohui Liao
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Peter G Smith
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas Institute for Neurological Discoveries, University of Kansas Medical Center, Kansas City, Kansas Kansas Intellectual and Developmental Disabilities Research Center, University of Kansas Medical Center, Kansas City, Kansas
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34
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Smith MT, Muralidharan A. Targeting angiotensin II type 2 receptor pathways to treat neuropathic pain and inflammatory pain. Expert Opin Ther Targets 2014; 19:25-35. [PMID: 25315162 DOI: 10.1517/14728222.2014.957673] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Neuropathic pain and chronic inflammatory pain are large unmet medical needs. Over the past two decades, numerous 'pain targets' have been identified for analgesic drug discovery. Despite promising results in rodent pain models, many compounds modulating such targets lacked efficacy in clinical trials. An exception is oral EMA401, a small-molecule angiotensin II type 2 receptor (AT2R) antagonist. AREAS COVERED Herein, angiotensin II/AT2R signaling-induced hyperexcitability and abnormal sprouting of cultured dorsal root ganglion neurons, together with radioligand binding, pharmacokinetics, analgesic efficacy and mode of action of small-molecule AT2R antagonists in rodent models of peripheral neuropathic and chronic inflammatory pain, are reviewed. The findings of a successful Phase IIa clinical trial of EMA401 in patients with neuropathic pain are presented in brief. EXPERT OPINION The functional importance of angiotensin II/AT2R signaling has remained enigmatic for decades, and there are no clinically available medications that target the AT2R. However, on the basis of preclinical findings and recent clinical trial data showing that the peripherally restricted, small-molecule AT2R antagonist, EMA401, successfully alleviated neuropathic pain in a Phase II clinical trial, the AT2R is receiving considerable attention as a new therapeutic target with human validation for the relief of peripheral neuropathic and chronic inflammatory pain conditions.
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Affiliation(s)
- Maree T Smith
- The University of Queensland, Centre for Integrated Preclinical Drug Development , St Lucia Campus, Brisbane, Queensland 4072 , Australia +61 7 33652554 ; +61 7 33467391 ;
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Langerhans cells regulate cutaneous innervation density and mechanical sensitivity in mouse footpad. Neurosci Lett 2014; 578:55-60. [PMID: 24970748 DOI: 10.1016/j.neulet.2014.06.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 05/26/2014] [Accepted: 06/09/2014] [Indexed: 11/21/2022]
Abstract
Langerhans cells are epidermal dendritic cells responsible for antigen presentation during an immune response. Langerhans cells associate intimately with epidermal sensory axons. While there is evidence that Langerhans cells may produce neurotrophic factors, a role in regulating cutaneous innervation has not been established. We used genetically engineered mice in which the diphtheria toxin (DT) receptor is targeted to Langerhans cells (Lang-DTR mice) to assess sensory axon-dendritic cell interactions. Diphtheria toxin administration to wild type mice did not affect epidermal structure, Langerhans cell content, or innervation density. A DT administration regimen supramaximal for completely ablating epidermal Langerhans cells in Lang-DTR mice reduced PGP 9.5-immunoreactive total innervation and calcitonin gene related peptide-immunoreactive peptidergic nociceptor innervation. Quantitative real-time polymerase chain reaction showed that epidermal gene expression of brain derived neurotrophic factor was unchanged, but nerve growth factor and glial cell line-derived neurotrophic factor mRNAs were reduced. Behavioral testing showed that, while thermal sensitivity was unaffected, mice depleted of Langerhans cells displayed mechanical hypersensitivity. These findings provide evidence that Langerhans cells play an important role in determining cutaneous sensory innervation density and mechanical sensitivity. This may involve alterations in neurotrophin production by Langerhans or other epidermal cells, which in turn may affect mechanical sensitivity directly or as a result of neuropathic changes.
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Affiliation(s)
| | - Cathrine Baastrup
- Danish Pain Research Center, Aarhus University, 8000 Aarhus C, Denmark
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Rice ASC, Dworkin RH, McCarthy TD, Anand P, Bountra C, McCloud PI, Hill J, Cutter G, Kitson G, Desem N, Raff M. EMA401, an orally administered highly selective angiotensin II type 2 receptor antagonist, as a novel treatment for postherpetic neuralgia: a randomised, double-blind, placebo-controlled phase 2 clinical trial. Lancet 2014; 383:1637-1647. [PMID: 24507377 DOI: 10.1016/s0140-6736(13)62337-5] [Citation(s) in RCA: 151] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Existing treatments for postherpetic neuralgia, and for neuropathic pain in general, are limited by modest efficacy and unfavourable side-effects. The angiotensin II type 2 receptor (AT2R) is a new target for neuropathic pain. EMA401, a highly selective AT2R antagonist, is under development as a novel neuropathic pain therapeutic agent. We assessed the therapeutic potential of EMA401 in patients with postherpetic neuralgia. METHODS In this multicentre, placebo-controlled, double-blind, randomised, phase 2 clinical trial, we enrolled patients (aged 22-89 years) with postherpetic neuralgia of at least 6 months' duration from 29 centres across six countries. We randomly allocated 183 participants to receive either oral EMA401 (100 mg twice daily) or placebo for 28 days. Randomisation was done according to a centralised randomisation schedule, blocked by study site, which was generated by an independent, unmasked statistician. Patients and staff at each site were masked to treatment assignment. We assessed the efficacy, safety, and pharmacokinetics of EMA401. The primary efficacy endpoint was change in mean pain intensity between baseline and the last week of dosing (days 22-28), measured on an 11-point numerical rating scale. The primary efficacy analysis was intention to treat. This trial is registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12611000822987. FINDINGS 92 patients were assigned to EMA401 and 91 were assigned to placebo. The patients given EMA401 reported significantly less pain compared with baseline values in the final week of treatment than did those given placebo (mean reductions in pain scores -2.29 [SD 1.75] vs -1.60 [1.66]; difference of adjusted least square means -0.69 [SE 0.25]; 95% CI -1.19 to -0.20; p=0.0066). No serious adverse events related to EMA401 occurred. Overall, 32 patients reported 56 treatment-emergent adverse events in the EMA401 group compared with 45 such events reported by 29 patients given placebo. INTERPRETATION EMA401 (100 mg twice daily) provides superior relief of postherpetic neuralgia compared with placebo at the end of 28 days of treatment. EMA401 was well tolerated by patients. FUNDING Spinifex Pharmaceuticals.
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Affiliation(s)
- Andrew S C Rice
- Pain Research, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, UK.
| | - Robert H Dworkin
- School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA
| | | | - Praveen Anand
- Peripheral Neuropathy Unit, Division of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Chas Bountra
- Structural Genomics Consortium and Department of Clinical Medicine, University of Oxford, Oxford, UK
| | | | - Julie Hill
- McCloud Consulting Group, Sydney, NSW, Australia
| | - Gary Cutter
- University of Alabama at Birmingham, Birmingham, AL, USA; Pythagoras, Birmingham, AL, USA
| | - Geoff Kitson
- Spinifex Pharmaceuticals, Melbourne, VIC, Australia
| | - Nuket Desem
- Spinifex Pharmaceuticals, Melbourne, VIC, Australia
| | - Milton Raff
- Christiaan Barnard Memorial Hospital, Cape Town, South Africa; Department of Anaesthesia, University of Cape Town, South Africa
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