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Adiponectin regulates electroacupuncture-produced analgesic effects in association with a crosstalk between the peripheral circulation and the spinal cord. Brain Behav Immun 2022; 99:43-52. [PMID: 34562596 DOI: 10.1016/j.bbi.2021.09.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 09/06/2021] [Accepted: 09/18/2021] [Indexed: 12/18/2022] Open
Abstract
Neurotransmitter-mediated acupuncture analgesia has been widely studied in nervous systems. It remains largely unclear if peripheral substances are involved the acupuncture analgesia. Adiponectin (APN), a circulating adipokine, shows analgesic effects. The study aimed to examine whether APN regulates analgesic effects of electroacupuncture (EA) in the complete Freund's adjuvant (CFA)-induced mouse model. APN wild type (WT) and knockout (KO) mouse were employed in the study. We found that EA attenuates the CFA-induced pain as demonstrated by the Hargreaves thermal test and the von Frey filament test. The deletion of APN significantly reduced the acupuncture analgesia in the CFA-treated APN KO mice while the intrathecal administration of APN mimicked the analgesic effects of EA. We further revealed that EA produced analgesic effects mainly via APN/AdipoR2-mediated AMPK pathway by the siRNA inhibitions of APN receptors (adipoR1/2) in the spinal cord. The immunofluorescence staining analysis showed that EA increased the APN accumulation in spinal cord through the blood circulation. In conclusion, the study indicates a novel mechanism that acupuncture produces analgesic effects at least partially via APN/AdipoR2-AMPK pathway in the spinal cord.
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Matsuura K, Sakai A, Watanabe Y, Mikahara Y, Sakamoto A, Suzuki H. Endothelin receptor type A is involved in the development of oxaliplatin-induced mechanical allodynia and cold allodynia acting through spinal and peripheral mechanisms in rats. Mol Pain 2021; 17:17448069211058004. [PMID: 34894846 PMCID: PMC8679041 DOI: 10.1177/17448069211058004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Oxaliplatin, a platinum-based chemotherapeutic agent, frequently causes severe
neuropathic pain typically encompassing cold allodynia and long-lasting mechanical
allodynia. Endothelin has been shown to modulate nociceptive transmission in a variety of
pain disorders. However, the action of endothelin varies greatly depending on many
variables, including pain causes, receptor types (endothelin type A (ETA) and B
(ETB) receptors) and organs (periphery and spinal cord). Therefore, in this
study, we investigated the role of endothelin in a Sprague–Dawley rat model of
oxaliplatin-induced neuropathic pain. Intraperitoneal administration of bosentan, a dual
ETA/ETB receptor antagonist, effectively blocked the development
or prevented the onset of both cold allodynia and mechanical allodynia. The preventive
effects were exclusively mediated by ETA receptor antagonism. Intrathecal
administration of an ETA receptor antagonist prevented development of
long-lasting mechanical allodynia but not cold allodynia. In marked contrast, an
intraplantar ETA receptor antagonist had a suppressive effect on cold allodynia
but only had a partial and transient effect on mechanical allodynia. In conclusion,
ETA receptor antagonism effectively prevented long-lasting mechanical
allodynia through spinal and peripheral actions, while cold allodynia was prevented
through peripheral actions.
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Affiliation(s)
- Kae Matsuura
- Department of Anesthesiology, 26367Nippon Medical School, Bunkyo-ku, Japan.,Department of Pharmacology, 26367Nippon Medical School, Bunkyo-ku, Japan
| | - Atsushi Sakai
- Department of Pharmacology, 26367Nippon Medical School, Bunkyo-ku, Japan
| | - Yuji Watanabe
- Department of Pharmacology, 26367Nippon Medical School, Bunkyo-ku, Japan
| | - Yasunori Mikahara
- Department of Pharmacology, 26367Nippon Medical School, Bunkyo-ku, Japan
| | - Atsuhiro Sakamoto
- Department of Anesthesiology, 26367Nippon Medical School, Bunkyo-ku, Japan
| | - Hidenori Suzuki
- Department of Pharmacology, 26367Nippon Medical School, Bunkyo-ku, Japan
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Gu P, Fan T, Wong SSC, Pan Z, Tai WL, Chung SK, Cheung CW. Central Endothelin-1 Confers Analgesia by Triggering Spinal Neuronal Histone Deacetylase 5 (HDAC5) Nuclear Exclusion in Peripheral Neuropathic Pain in Mice. THE JOURNAL OF PAIN 2021; 22:454-471. [PMID: 33421591 DOI: 10.1016/j.jpain.2020.12.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 10/06/2020] [Accepted: 12/14/2020] [Indexed: 11/17/2022]
Abstract
The rationale of spinal administration of endothelin-1(ET-1) mediated anti-nociceptive effect has not been elucidated. ET-1 is reported to promote nuclear effluxion of histone deacetylase 5 (HDAC5) in myocytes, and spinal HDAC5 is implicated in modulation of pain processing. In this study, we aimed to investigate whether central ET-1 plays an anti-nociceptive role by facilitating spinal HDAC5 nuclear shuttling under neuropathic pain. Here, we demonstrate that upregulating spinal ET-1 attenuated the nociception induced by partial sciatic nerve ligation surgery and this analgesic effect mediated by ET-1 was attenuated by intrathecal injection of endothelin A receptor selective inhibitor (BQ123) or by blocking the exportation of nuclear HDAC5 by adeno-associated viruses targeting neuronal HDAC5 (AVV-HDAC5 S259/498A Mutant). Notably, ET-1 administration increased spinal glutamate acid decarboxylases (GAD65/67) expression via initiating HDAC5 nuclear exportation and increased the acetylation of histone 3 at lysine 9 (Acetyl-H3K9) in the promotor regions of spinal Gad1 and Gad2 genes. This was reversed by blocking endothelin A receptor function or by inhibiting the spinal neuronal nuclear exportation of HDAC5. Therefore, inducing spinal GABAergic neuronal HDAC5 nuclear exportation may be a novel therapeutic approach for managing neuropathic pain. PERSPECTIVE: Neuropathic pain is intractable in a clinical setting, and epigenetic regulation is considered to contribute to this processing. Characterizing the anti-nociceptive effect of ET-1 and investigating the associated epigenetic mechanisms in animal models may lead to the development of new therapeutic strategies and targets for treating neuropathic pain.
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Affiliation(s)
- Pan Gu
- Department of Anaesthesiology, The University of Hong Kong, HKSAR, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, HKSAR, China; Department of Anaesthesiology, The University of Hong Kong-Shenzhen Hospital, Guangdong province, China
| | - Tingting Fan
- Department of Anaesthesiology, The University of Hong Kong, HKSAR, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, HKSAR, China
| | - Stanley Sau Ching Wong
- Department of Anaesthesiology, The University of Hong Kong, HKSAR, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, HKSAR, China
| | - Zhiqiang Pan
- Jiangsu Province Key Laboratory of Anaesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Wai Lydia Tai
- Department of Anaesthesiology, The University of Hong Kong, HKSAR, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, HKSAR, China; Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts
| | - Sookja Kim Chung
- Macau University of Science and Technology, Taipa, Macau; School of Biomedical Sciences, The State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong
| | - Chi Wai Cheung
- Department of Anaesthesiology, The University of Hong Kong, HKSAR, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, HKSAR, China; Research Centre of Heart, Brain, Hormone & Healthy Aging, The University of Hong Kong, HKSAR, China; Department of Anaesthesiology, The University of Hong Kong-Shenzhen Hospital, Guangdong province, China.
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4
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Xu B, Liu SS, Wei J, Jiao ZY, Mo C, Lv CM, Huang AL, Chen QB, Ma L, Guan XH. Role of Spinal Cord Akt-mTOR Signaling Pathways in Postoperative Hyperalgesia Induced by Plantar Incision in Mice. Front Neurosci 2020; 14:766. [PMID: 32848550 PMCID: PMC7396510 DOI: 10.3389/fnins.2020.00766] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 06/29/2020] [Indexed: 12/29/2022] Open
Abstract
Poor postoperative pain (POP) control increases perioperative morbidity, prolongs hospitalization days, and causes chronic pain. However, the specific mechanism(s) underlying POP is unclear and the identification of optimal perioperative treatment remains elusive. Akt and mammalian target of rapamycin (mTOR) are expressed in the spinal cord, dorsal root ganglion, and sensory axons. In this study, we explored the role of Akt and mTOR in pain-related behaviors induced by plantar incision in mice. Plantar incision activated spinal Akt and mTOR in a dose-dependent manner. Pre-treatment with Akt inhibitors intrathecally prevented the activation of mTOR dose-dependently. In addition, blocking the Akt-mTOR signaling cascade attenuated pain-related behaviors and spinal Fos protein expression induced by plantar incision. Our observations demonstrate that Akt-mTOR might be a potential therapeutic target for the treatment of POP.
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Affiliation(s)
- Bing Xu
- Department of Rehabilitation, The People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
| | - Su-Su Liu
- Department of Anesthesiology, The People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
| | - Jin Wei
- Department of Anesthesiology, The People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
| | - Zi-Yin Jiao
- Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Cheng Mo
- Department of Anesthesiology, The People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
| | - Cheng-Mei Lv
- Department of Anesthesiology, The People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
| | - Ai-Lan Huang
- Department of Anesthesiology, The People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
| | - Qi-Bo Chen
- Department of Rehabilitation, The People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
| | - Li Ma
- Department of Anesthesiology, The People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
| | - Xue-Hai Guan
- Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
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Pontes RB, Lisboa MRP, Pereira AF, Lino JA, de Oliveira FFB, de Mesquita AKV, de Freitas Alves BW, Lima-Júnior RCP, Vale ML. Involvement of Endothelin Receptors in Peripheral Sensory Neuropathy Induced by Oxaliplatin in Mice. Neurotox Res 2019; 36:688-699. [PMID: 31228092 DOI: 10.1007/s12640-019-00074-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 05/24/2019] [Accepted: 06/11/2019] [Indexed: 01/10/2023]
Abstract
The aim of this study was to evaluate the participation of the endothelin ETA and ETB receptors and the effects of bosentan in oxaliplatin-induced peripheral sensory neuropathy (OIN) in mice. Adult male Swiss mice received 1 mg/kg of oxaliplatin intravenously, twice a week for 5 weeks. Dorsal root ganglia (DRG) and spinal cords were removed for evaluation of the endothelin ETA and ETB receptor expression. Afterwards, selective (BQ-123 and BQ-788; 10 nmol in 30 μL, intraplantarly) and non-selective (bosentan, 100 mg/kg, orally) antagonists were administered in order to evaluate the involvement of the endothelin receptors in OIN. Mechanical and thermal nociception tests were performed once a week for 56 days. Oxaliplatin induced mechanical and thermal hypersensitivity and increased the endothelin ETA receptor expression in both the DRG and spinal cord (P < 0.05). Endothelin ETB receptor expression was increased in the DRG (P < 0.05) but not in the spinal cord. Both endothelin ETA and ETB receptor selective antagonists partially prevented mechanical hyperalgesia in mice with OIN (P < 0.05). Moreover, bosentan prevented mechanical and thermal hypersensitivity in oxaliplatin-treated mice (P < 0.05). In conclusion, both endothelin ETA and ETB receptors seem to be involved in the OIN in mice and they should be considered possible targets for the management of this clinical feature.
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Affiliation(s)
- Renata Bessa Pontes
- Department of Physical Therapy, Faculty of Medicine, Federal University of Ceará, Fortaleza, CE, 60430-160, Brazil
| | - Mario Roberto Pontes Lisboa
- Department of Morphology, Faculty of Medicine, Federal University of Ceará, Fortaleza, CE, 60430-170, Brazil
| | - Anamaria Falcão Pereira
- Department of Physiology and Pharmacology, Faculty of Medicine, Federal University of Ceará (UFC), R. Cel. Nunes de Melo, 1127, Rodolfo Teófilo, Fortaleza, CE, 60430-270, Brazil
| | - Juliana Arcanjo Lino
- Department of Clinical Medicine, Faculty of Medicine, Federal University of Ceará, Fortaleza, CE, 60430-140, Brazil
| | - Francisco Fábio Bezerra de Oliveira
- Department of Physiology and Pharmacology, Faculty of Medicine, Federal University of Ceará (UFC), R. Cel. Nunes de Melo, 1127, Rodolfo Teófilo, Fortaleza, CE, 60430-270, Brazil
| | | | | | - Roberto César Pereira Lima-Júnior
- Department of Physiology and Pharmacology, Faculty of Medicine, Federal University of Ceará (UFC), R. Cel. Nunes de Melo, 1127, Rodolfo Teófilo, Fortaleza, CE, 60430-270, Brazil
| | - Mariana Lima Vale
- Department of Morphology, Faculty of Medicine, Federal University of Ceará, Fortaleza, CE, 60430-170, Brazil.
- Department of Physiology and Pharmacology, Faculty of Medicine, Federal University of Ceará (UFC), R. Cel. Nunes de Melo, 1127, Rodolfo Teófilo, Fortaleza, CE, 60430-270, Brazil.
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6
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Liu YD, Wang ZB, Han G, Jin L, Zhao P. Hyperbaric oxygen relieves neuropathic pain through AKT/TSC2/mTOR pathway activity to induce autophagy. J Pain Res 2019; 12:443-451. [PMID: 30774414 PMCID: PMC6361320 DOI: 10.2147/jpr.s189353] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Background Our previous study suggested that HBO treatment attenuated neuropathic pain by inhibiting mTOR to induce autophagy in SNL neuropathic pain model. The aim of this study was to evaluate the role of AKT/TSC2/mTOR pathway in SNL and autophagy and determine whether HBO treatment could relieve neuropathic pain via modulating AKT/TSC2/mTOR pathway. Materials and methods Rats were randomly divided into sham, SNL, SNL + HBO treatment, SNL + vehicle, and SNL + AKT inhibitor groups. Neuropathic pain was induced following SNL procedure. Rats in the SNL + HBO group received HBO treatment for 7 consecutive days beginning on postoperative day 1. The SNL + vehicle group received 10 µL of 3% dimethyl sulfoxide in saline. SNL + AKT inhibitor group received 10 µL AKT inhibitor IV intrathecally. Mechanical withdrawal threshold tests were performed to evaluate mechanical hypersensitivity. AKT, p-AKT, TSC2, mTOR, p-mTOR, and LC3-II protein expressions were examined by Western blot analysis. Results HBO reversed AKT/TSC2/mTOR upregulation induced by SNL and attenuated neuropathic pain. Intrathecal injection of AKT inhibitor IV decreased the activity of AKT/TSC2/mTOR pathway and increased LC3-II expression accompanied by analgesic effect in SNL rats. Conclusion Taken together, our findings demonstrated AKT/TSC2/mTOR pathway was activated in SNL-induced neuropathic pain, and HBO treatment attenuated neuropathic pain via neutralizing AKT/TSC2/mTOR pathway activation.
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Affiliation(s)
- Yong-Da Liu
- Department of Anesthesiology and Pain Management, Shengjing Hospital of China Medical University, Shenyang 110004, China,
| | - Zhi-Bin Wang
- Department of Anesthesiology and Pain Management, Shengjing Hospital of China Medical University, Shenyang 110004, China,
| | - Guang Han
- Department of Anesthesiology and Pain Management, Shengjing Hospital of China Medical University, Shenyang 110004, China,
| | - Li Jin
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
| | - Ping Zhao
- Department of Anesthesiology and Pain Management, Shengjing Hospital of China Medical University, Shenyang 110004, China,
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7
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Mazzardo-Martins L, Salm DC, Winkelmann-Duarte EC, Ferreira JK, Lüdtke DD, Frech KP, Belmonte LAO, Horewicz VV, Piovezan AP, Cidral-Filho FJ, Moré AOO, Martins DF. Electroacupuncture induces antihyperalgesic effect through endothelin-B receptor in the chronic phase of a mouse model of complex regional pain syndrome type I. Pflugers Arch 2018; 470:1815-1827. [DOI: 10.1007/s00424-018-2192-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 07/12/2018] [Accepted: 08/02/2018] [Indexed: 01/13/2023]
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8
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Tai LW, Pan Z, Sun L, Li H, Gu P, Wong SSC, Chung SK, Cheung CW. Suppression of Pax2 Attenuates Allodynia and Hyperalgesia through ET-1-ETAR-NFAT5 Signaling in a Rat Model of Neuropathic Pain. Neuroscience 2018; 384:139-151. [PMID: 29847776 DOI: 10.1016/j.neuroscience.2018.05.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 05/15/2018] [Accepted: 05/16/2018] [Indexed: 01/16/2023]
Abstract
Endothelin-1 (ET-1) and its receptors (ETAR/ETBR) emerge to be a key signaling axis in neuropathic pain processing and are recognized as new therapeutic targets. Yet, little is known on the functional regulation of ET-1 axis during neuropathic pain. Bioinformatics analysis indicated that paired box gene 2 (Pax2) or nuclear factor of activated T-cells 5 (NFAT5), two transcription factors involved in the modulation of neurotransmission, may regulate ET-1. Therefore, we hypothesized that ET-1 axis may be regulated by Pax2 or NFAT5 in the development of neuropathic pain. After partial sciatic nerve ligation (pSNL), rats displayed allodynia and hyperalgesia, which was associated with increased mRNA and protein expressions of spinal Pax2, NFAT5, and mRNA levels of ET-1 and ETAR, but not ETBR. Knockdown of Pax2 or NFAT5 with siRNA, or inhibition of ETAR with BQ-123 attenuated pSNL-induced pain-like behaviors. At molecular level, Pax2 siRNA, but not NFAT5 siRNA, downregulated ET-1 and ETAR, while ETAR inhibitor reduced NFAT5, indicating Pax2 in the upstream of ET-1 axis with NFAT5 in the downstream. Further, suppression of Pax2 (inhibiting ET-1) or impairment of ET-1 signaling (inhibition of ETAR and/or decrease of NFAT5) deactivated mitogen-activated protein kinases (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways, supporting the significance of functional regulation of ET-1 axis in neuropathic pain signaling. These findings demonstrate that Pax2 targeting ET-1-ETAR-NFAT5 is a novel regulatory mechanism underlying neuropathic pain.
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Affiliation(s)
- Lydia Wai Tai
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, Hong Kong, China
| | - Zhiqiang Pan
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, Hong Kong, China; Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Liting Sun
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, Hong Kong, China
| | - Haobo Li
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong, China
| | - Pan Gu
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, Hong Kong, China
| | - Stanley Sau Ching Wong
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, Hong Kong, China
| | - Sookja K Chung
- Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, Hong Kong, China; School of Biomedical Sciences, Hormone and Healthy Aging, The University of Hong Kong, Hong Kong, China; Research Center of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, Hong Kong, China
| | - Chi Wai Cheung
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, Hong Kong, China.
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9
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Han MM, Yang CW, Cheung CW, Li J. Blockage of spinal endothelin A receptors attenuates bone cancer pain via regulation of the Akt/ERK signaling pathway in mice. Neuropeptides 2018; 68:36-42. [PMID: 29395120 DOI: 10.1016/j.npep.2018.01.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/17/2017] [Accepted: 01/21/2018] [Indexed: 10/18/2022]
Abstract
Bone cancer pain (BCP) is a common source of pain in patients with advanced stage and metastatic cancer; however, existing treatment for this kind of pain remains deficient. Being closely related to sensory change and inflammatory pain in both the central and peripheral nervous systems, endothelin A receptor (ETAR) plays an essential role in pain processing. As a result, ETAR antagonist has been reported to alleviate both neuropathic and inflammatory pain. Thus far, the role of ETAR in the process of BCP is still ambiguous. In this study, by using a BCP mouse model, the analgesic effect and molecular mechanism of the ETAR antagonist BQ-123 was investigated. Pain sensation in the BCP mouse model was investigated by the number of spontaneous flinches (NSF) and pain withdrawal threshold (PWT), and the mechanism of BCP was assessed by measuring p-Akt, p-Akt/t-Akt, p-ERK-1/2 and p-ERK-1/2/t-ERK-1/2 levels in L4-6 segments of the spinal cord. Our results demonstrated that BCP mice showed a higher NSF and a lower PWT score than Sham mice. In addition to the development of nociceptive sensitization, p-Akt, p-Akt/t-Akt, p-ERK-1/2 and p-ERK-1/2/t-ERK-1/2 were up-regulated correspondingly in L4-6 segments of the spinal cord in BCP mice. BQ-123 treatment showed a promising analgesic effect, and the effect was correlated to the down-regulation of p-Akt, p-Akt/t-Akt, p-ERK-1/2 and p-ERK-1/2/t-ERK-1/2 in spinal cord cells. The results suggested that intrathecal administration of BQ-123 was able to relieve BCP in mice as a consequence of suppressing the Akt and ERK signalling pathways.
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Affiliation(s)
- Ming-Ming Han
- School of Medicine, Shandong University, Jinan, Shandong, China; Department of Anesthesiology, Anhui Provincial Hospital, Anhui Medical University, Hefei, China
| | - Cheng-Wei Yang
- School of Medicine, Shandong University, Jinan, Shandong, China; Department of Anesthesiology, Anhui Provincial Hospital, Anhui Medical University, Hefei, China
| | - Chi-Wai Cheung
- Department of Anesthesiology, The University of Hong Kong, Hong Kong, China; Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, Hong Kong, China; Research Center of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, Hong Kong, China
| | - Juan Li
- Department of Anesthesiology, Anhui Provincial Hospital, Anhui Medical University, Hefei, China; School of Medicine, Shandong University, Jinan, Shandong, China.
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10
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Endothelin-1 Induces Degeneration of Cultured Motor Neurons Through a Mechanism Mediated by Nitric Oxide and PI3K/Akt Pathway. Neurotox Res 2017; 32:58-70. [PMID: 28285347 DOI: 10.1007/s12640-017-9711-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 02/08/2017] [Accepted: 02/23/2017] [Indexed: 12/13/2022]
Abstract
Endothelin-1 (ET-1) is a vasoactive peptide produced by activated astrocytes and microglia and is implicated in initiating and sustaining reactive gliosis in neurodegenerative diseases. We have previously suggested that ET-1 can play a role in the pathophysiology of amyotrophic lateral sclerosis (ALS). Indeed, we reported that this peptide is abundantly expressed in reactive astrocytes in the spinal cord of SOD1-G93A mice and ALS patients and exerts a toxic effect on motor neurons (MNs) in an in vitro model of mixed spinal cord cultures enriched with reactive astrocytes. Here, we explored the possible mechanisms underlying the toxic effect of ET-1 on cultured MNs. We show that ET-1 toxicity is not directly caused by oxidative stress or activation of cyclooxygenase-2 but requires the synthesis of nitric oxide and is mediated by a reduced activation of the phosphoinositide 3-kinase pathway. Furthermore, we observed that ET-1 is also toxic for microglia, although its effect on MNs is independent of the presence of this type of glial cells. Our study confirms that ET-1 may contribute to MN death and corroborates the view that the modulation of ET-1 signaling might be a therapeutic strategy to slow down MN degeneration in ALS.
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11
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The pathophysiological role of astrocytic endothelin-1. Prog Neurobiol 2016; 144:88-102. [DOI: 10.1016/j.pneurobio.2016.04.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/23/2016] [Accepted: 04/25/2016] [Indexed: 12/13/2022]
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12
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Davenport AP, Hyndman KA, Dhaun N, Southan C, Kohan DE, Pollock JS, Pollock DM, Webb DJ, Maguire JJ. Endothelin. Pharmacol Rev 2016; 68:357-418. [PMID: 26956245 PMCID: PMC4815360 DOI: 10.1124/pr.115.011833] [Citation(s) in RCA: 462] [Impact Index Per Article: 57.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The endothelins comprise three structurally similar 21-amino acid peptides. Endothelin-1 and -2 activate two G-protein coupled receptors, ETA and ETB, with equal affinity, whereas endothelin-3 has a lower affinity for the ETA subtype. Genes encoding the peptides are present only among vertebrates. The ligand-receptor signaling pathway is a vertebrate innovation and may reflect the evolution of endothelin-1 as the most potent vasoconstrictor in the human cardiovascular system with remarkably long lasting action. Highly selective peptide ETA and ETB antagonists and ETB agonists together with radiolabeled analogs have accurately delineated endothelin pharmacology in humans and animal models, although surprisingly no ETA agonist has been discovered. ET antagonists (bosentan, ambrisentan) have revolutionized the treatment of pulmonary arterial hypertension, with the next generation of antagonists exhibiting improved efficacy (macitentan). Clinical trials continue to explore new applications, particularly in renal failure and for reducing proteinuria in diabetic nephropathy. Translational studies suggest a potential benefit of ETB agonists in chemotherapy and neuroprotection. However, demonstrating clinical efficacy of combined inhibitors of the endothelin converting enzyme and neutral endopeptidase has proved elusive. Over 28 genetic modifications have been made to the ET system in mice through global or cell-specific knockouts, knock ins, or alterations in gene expression of endothelin ligands or their target receptors. These studies have identified key roles for the endothelin isoforms and new therapeutic targets in development, fluid-electrolyte homeostasis, and cardiovascular and neuronal function. For the future, novel pharmacological strategies are emerging via small molecule epigenetic modulators, biologicals such as ETB monoclonal antibodies and the potential of signaling pathway biased agonists and antagonists.
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Affiliation(s)
- Anthony P Davenport
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Kelly A Hyndman
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Neeraj Dhaun
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Christopher Southan
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Donald E Kohan
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Jennifer S Pollock
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - David M Pollock
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - David J Webb
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Janet J Maguire
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
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Luo X, Tai WL, Sun L, Pan Z, Xia Z, Chung SK, Cheung CW. Crosstalk between astrocytic CXCL12 and microglial CXCR4 contributes to the development of neuropathic pain. Mol Pain 2016; 12:12/0/1744806916636385. [PMID: 27030717 PMCID: PMC4956184 DOI: 10.1177/1744806916636385] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 01/22/2016] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Chemokine axis chemokine C-X-C motif ligand 12/C-X-C chemokine receptor type 4 (CXCL12/CXCR4) is an emerging pain modulator, but mechanisms for its involvement in neuropathic pain remain unclear. Here, we aimed to study whether CXCL12/CXCR4 axis modulated the development of neuropathic pain via glial mechanisms. In this study, two mouse models of neuropathic pain, namely partial sciatic nerve ligation (pSNL) model and chronic post-ischemia pain (CPIP) model, were used. RESULTS In the dorsal horn of L3-L5 segment of spinal cord, CXCL12 and CXCR4 were expressed in both astrocyte and microglia in normal mice. In the pSNL or CPIP model, the expression level of CXCL12 in the ipsilateral L3-L5 segment of mice spinal cord was increased in an astrocyte-dependent manner on post-operative day (POD) 3. Intrathecal administration of CXCL12 with AMD3100 (CXCR4 antagonist) or minocycline (microglia activation inhibitor), but not fluorocitrate (astrocyte activation inhibitor), reversed CXCL12-indued mechanical allodynia in naïve mice. In these models, AMD3100 and AMD3465 (CXCR4 antagonist), administered daily from 1 h before surgery and up to POD 3, attenuated the development of mechanical allodynia. Moreover, AMD3100 administered daily from 1 h before surgery and up to POD 3 downregulated mRNA levels of tumor necrosis factor alpha, interleukin 1β, and interleukin 6 in the ipsilateral L3-L5 segment of spinal cord in the pSNL and CPIP models on POD 3. CONCLUSION This study demonstrates the crosstalk between astrocytic CXCL12 and microglial CXCR4 in the pathogenesis of neuropathic pain using pSNL and CPIP models. Our results offer insights for the future research on CXCL12/CXCR4 axis and neuropathic pain therapy.
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Affiliation(s)
- Xin Luo
- Department of Anaesthesiology, The University of Hong Kong, HKSAR, China Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, HKSAR, China
| | - Wai L Tai
- Department of Anaesthesiology, The University of Hong Kong, HKSAR, China Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, HKSAR, China
| | - Liting Sun
- Department of Anaesthesiology, The University of Hong Kong, HKSAR, China Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, HKSAR, China
| | - Zhiqiang Pan
- Department of Anesthesiology, Xuzhou Medical University, Jiangsu Province, China
| | - Zhengyuan Xia
- Department of Anaesthesiology, The University of Hong Kong, HKSAR, China Research Center of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, HKSAR, China
| | - Sookja K Chung
- Laboratory and Clinical Research Institute for Pain, The University of Hong Kong, HKSAR, China Research Center of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, HKSAR, China Department of Anatomy, The University of Hong Kong, HKSAR, China
| | - Chi Wai Cheung
- Department of Anaesthesiology, The University of Hong Kong, HKSAR, China Research Center of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, HKSAR, China Department of Anatomy, The University of Hong Kong, HKSAR, China
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Jiang SP, Zhang ZD, Kang LM, Wang QH, Zhang L, Chen HP. Celecoxib reverts oxaliplatin-induced neuropathic pain through inhibiting PI3K/Akt2 pathway in the mouse dorsal root ganglion. Exp Neurol 2016; 275 Pt 1:11-6. [DOI: 10.1016/j.expneurol.2015.11.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 10/29/2015] [Accepted: 11/02/2015] [Indexed: 02/07/2023]
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15
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Serafim KGG, Navarro SA, Zarpelon AC, Pinho-Ribeiro FA, Fattori V, Cunha TM, Alves-Filho JC, Cunha FQ, Casagrande R, Verri WA. Bosentan, a mixed endothelin receptor antagonist, inhibits superoxide anion-induced pain and inflammation in mice. Naunyn Schmiedebergs Arch Pharmacol 2015; 388:1211-21. [PMID: 26246053 DOI: 10.1007/s00210-015-1160-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 07/27/2015] [Indexed: 01/24/2023]
Abstract
Bosentan is a mixed endothelin receptor antagonist widely used to treat patients with pulmonary arterial hypertension, and the emerging literature suggests bosentan as a potent anti-inflammatory drug. Superoxide anion is produced in large amounts during inflammation, stimulates cytokine production, and thus contributes to inflammation and pain. However, it remains to be determined whether endothelin contributes to the inflammatory response triggered by the superoxide anion. The present study investigated the effects of bosentan in a mouse model of inflammation and pain induced by potassium superoxide, a superoxide anion donor. Male Swiss mice were treated with bosentan (10-100 mg/kg) by oral gavage, 1 h before potassium superoxide injection, and the inflammatory response was evaluated locally and at spinal cord (L4-L6) levels. Bosentan (100 mg/kg) inhibited superoxide anion-induced mechanical and thermal hyperalgesia, overt pain-like behavior (abdominal writhings, paw flinching, and licking), paw edema, myeloperoxidase activity (neutrophil marker) in the paw skin, and leukocyte recruitment in the peritoneal cavity. Bosentan also inhibited superoxide anion-induced interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) production, while it enhanced IL-10 production in the paw skin and spinal cord. Bosentan inhibited the reduction of antioxidant capacity (reduced glutathione, ferric reducing antioxidant power, and ABTS radical scavenging ability) induced by the superoxide anion. Finally, we demonstrated that intraplantar injection of potassium superoxide induces the mRNA expression of prepro-endothelin-1 in the paw skin and spinal cord. In conclusion, our results demonstrated that superoxide anion-induced inflammation, pain, cytokine production, and oxidative stress depend on endothelin; therefore, these responses are amenable to bosentan treatment.
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Affiliation(s)
- Karla G G Serafim
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Rod. Celso Garcia Cid PR445 KM380, Londrina, Paraná, 86057-970, Brazil
| | - Suelen A Navarro
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Rod. Celso Garcia Cid PR445 KM380, Londrina, Paraná, 86057-970, Brazil
| | - Ana C Zarpelon
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Rod. Celso Garcia Cid PR445 KM380, Londrina, Paraná, 86057-970, Brazil
| | - Felipe A Pinho-Ribeiro
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Rod. Celso Garcia Cid PR445 KM380, Londrina, Paraná, 86057-970, Brazil
| | - Victor Fattori
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Rod. Celso Garcia Cid PR445 KM380, Londrina, Paraná, 86057-970, Brazil
| | - Thiago M Cunha
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil
| | - Jose C Alves-Filho
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil
| | - Fernando Q Cunha
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil
| | - Rubia Casagrande
- Departamento de Ciências Farmacêuticas, Centro de Ciências da Saúde, Hospital Universitário, Universidade Estadual de Londrina, Av. Robert Koch, 60, Londrina, Paraná, 86038-350, Brazil
| | - Waldiceu A Verri
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Rod. Celso Garcia Cid PR445 KM380, Londrina, Paraná, 86057-970, Brazil.
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16
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Hung VKL, Tai LW, Luo X, Wang XM, Chung SK, Cheung CW. Targeted Overexpression of Astrocytic Endothelin-1 Attenuates Neuropathic Pain by Upregulating Spinal Excitatory Amino Acid Transporter-2. J Mol Neurosci 2015; 57:90-6. [PMID: 25994587 DOI: 10.1007/s12031-015-0581-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 05/14/2015] [Indexed: 12/11/2022]
Abstract
We previously demonstrated that endogenous endothelin-1 (ET-1) inhibits pathological pain in a transgenic mouse model with astrocyte-specific ET-1 overexpression (GET-1 mice); however, the underlying mechanism is unclear. ET-1 regulates excitatory amino acid transporter-2 (EAAT-2), a predominant subtype of glutamate transporters that plays critical role in pain modulation in spinal astrocytes. We hypothesized that astrocytic ET-1 overexpression alleviates neuropathic pain through modulating EAAT-2. GET-1 or nontransgenic (NTg) mice either received sham operation or sciatic nerve ligation (SNL) with or without ceftriaxone (CEF, an EAAT-2 inducer, for 4 days before termination). In GET-1 mice, mRNA and protein expressions of EAAT-2, but not EAAT-1, were upregulated associated with reduced SNL-induced neuropathic pain. Despite that SNL induced a significant reduction of EAAT-2 mRNA expression in both genotypes of mice, post-SNL EAAT-2 mRNA expression was higher in GET-1 mice than that in NTg mice. EAAT-2 induction by CEF reduced SNL-induced neuropathic pain in both NTg and GET-1 mice. In cultured rat astrocytic cell line, overexpression of ET-1 mRNA expression also elevated EAAT-2 mRNA expression, which was reversed by ET receptor antagonists. In conclusion, overexpressed astrocytic ET-1 suppressed neuropathic pain by upregulating spinal EAAT-2 expression via ET receptors.
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Affiliation(s)
- Victor K L Hung
- Department of Anaesthesiology, The University of Hong Kong, Rm 424, 4/F, Block K, Queen Mary Hospital, 102, Pokfulam, HKSAR, China
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