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Bilgin B, Adam M, Hekim MG, Bulut F, Ozcan M. Gadolinium-based contrast agents aggravate mechanical and thermal hyperalgesia in a nitroglycerine-induced migraine model in male mice. Magn Reson Imaging 2024; 111:67-73. [PMID: 38604348 DOI: 10.1016/j.mri.2024.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 03/26/2024] [Accepted: 04/05/2024] [Indexed: 04/13/2024]
Abstract
In the diagnosis of migraine, which is a neurovascular disease, gadolinium-based contrast agents (GBCAs) are used to rule out more serious conditions. On the other hand, it remains unclear as a scientific gap whether GBCAs may trigger migraine-related pain. The aim of this study was to investigate the effect of GBCAs on mechanical and thermal pain behaviour in a nitroglycerin (NTG)-induced migraine model in mice. NTG (10 mg/kg) was administered intraperitoneally to adult (6-8weeks old) BALB/c mice 2 h before behavioral tests 5 times every other day on days 1st, 3rd, 5th and 9th to induce migraine model (N = 50). As GBCAs, gadobenate dimeglumine (linear-ionic), Gadodiamide (linear-nonionic), and gadobutrol (macrocyclic-nonionic) were delivered intravenously through the tail vein of mice for 5 days on test days. Mechanical pain threshold (plantar and facial withdrawal threshold) was evaluated by plantar von Frey and periorbital von Frey tests on days 1st, 5th, and 9th, and thermal pain threshold (latency) was evaluated by hot plate and cold plate tests on days 3rd and 7th. There was a statistically significant increase in mechanical and thermal hyperalgesia in NTG administered groups compared to the control group. Gadodiamide, gadobutrol and gadobenate dimeglumine administration significantly decreased latency, paw and facial withdrawal threshold (0.18 ± 0.05, 0.17 ± 0.07, 0.16 ± 0.09; 9th day values respectively) compared to NTG group (0.27 ± 0.05). The results of this in vivo study show that GBCAs produce effects that may trigger migraine attacks in migraine. It is recommended that these effects be further investigated and supported by further clinical studies.
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Affiliation(s)
- Batuhan Bilgin
- Gaziantep Islam Science and Technology University Faculty of Medicine, Department of Biophysics, Gaziantep, Turkey.
| | - Muhammed Adam
- Firat University Faculty of Medicine, Department of Biophysics, Elazig, Turkey
| | | | - Ferah Bulut
- Firat University Faculty of Medicine, Department of Biophysics, Elazig, Turkey
| | - Mete Ozcan
- Firat University Faculty of Medicine, Department of Biophysics, Elazig, Turkey
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2
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Saloman JL, Epouhe AY, Ruff CF, Albers KM. PDX1, a transcription factor essential for organ differentiation, regulates SERCA-dependent Ca 2+ homeostasis in sensory neurons. Cell Calcium 2024; 120:102884. [PMID: 38574509 PMCID: PMC11188734 DOI: 10.1016/j.ceca.2024.102884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 03/13/2024] [Accepted: 03/31/2024] [Indexed: 04/06/2024]
Abstract
Pancreatic and duodenal homeobox 1 (PDX1) is a transcription factor required for the development and differentiation of the pancreas. Previous studies indicated that PDX1 expression was restricted to the gastrointestinal tract. Using a cre-dependent reporter, we observed PDX1-dependent expression of tdtomato (PDX1-tom) in a subpopulation of sensory nerves. Many of these PDX1-tom afferents expressed the neurofilament 200 protein and projected to the skin. Tdtomato-labeled terminals were associated with hair follicles in the form of longitudinal and circumferential lanceolate endings suggesting a role in tactile and proprioceptive perception. To begin to examine the functional significance of PDX1 in afferents, we used Fura-2 imaging to examine calcium (Ca2+) handling under naïve and nerve injury conditions. Neuropathic injury is associated with increased intracellular Ca2+ signaling that in part results from dysregulation of the sarco/endoplasmic reticulum calcium transport ATPase (SERCA). Here we demonstrate that under naïve conditions, PDX1 regulates expression of the SERCA2B isoform in sensory neurons. In response to infraorbital nerve injury, a significant reduction of PDX1 and SERCA2B expression and dysregulation of Ca2+ handling occurs in PDX1-tom trigeminal ganglia neurons. The identification of PDX1 expression in the somatosensory system and its regulation of SERCA2B and Ca2+ handling provide a new mechanism to explain pathological changes in primary afferents that may contribute to pain associated with nerve injury.
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Affiliation(s)
- Jami L Saloman
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Neurobiology, Center for Neuroscience and Center for Pain Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
| | - Ariel Y Epouhe
- Department of Neurobiology, Center for Neuroscience and Center for Pain Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Catherine F Ruff
- Department of Neurobiology, Center for Neuroscience and Center for Pain Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Kathryn M Albers
- Department of Neurobiology, Center for Neuroscience and Center for Pain Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Kochi T, Nakamura Y, Ma S, Uemoto S, Hisaoka-Nakashima K, Irifune M, Morioka N. Mirogabalin alleviates nociceptive hypersensitivity without causing sedation in a mouse model of post-traumatic trigeminal neuropathy. Behav Brain Res 2022; 425:113829. [DOI: 10.1016/j.bbr.2022.113829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 11/02/2022]
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Yazğan Y, Nazıroğlu M. Involvement of TRPM2 in the Neurobiology of Experimental Migraine: Focus on Oxidative Stress and Apoptosis. Mol Neurobiol 2021; 58:5581-5601. [PMID: 34370177 DOI: 10.1007/s12035-021-02503-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 07/20/2021] [Indexed: 12/16/2022]
Abstract
Excessive Ca2+ influx and mitochondrial oxidative stress (OS) of trigeminal ganglia (TG) have essential roles in the etiology of migraine headache and aura. The stimulation of TRPM2 channel via the generation of OS and ADP-ribose (ADPR) induces pain, inflammatory, and oxidative neurotoxicity, although its inhibition reduces the intensity of pain and neurotoxicity in several neurons. However, the cellular and molecular effects of TRPM2 in the TG of migraine model (glyceryl trinitrate, GTN) on the induction of pain, OS, apoptosis, and inflammation remain elusive. GTN-mediated increases of pain intensity, apoptosis, death, cytosolic reactive oxygen species (ROS), mitochondrial ROS, caspase -3, caspase -9, cytosolic Ca2+ levels, and cytokine generations (TNF-α, IL-1β, and IL-6) in the TG of TRPM2 wild-type mouse were further increased by the TRPM2 activation, although they were modulated by the treatments of GSH, PARP-1 inhibitors (PJ34 and DPQ), and TRPM2 blockers (ACA and 2APB). However, the effects of GTN were not observed in the TG of TRPM2 knockout mice. The current data indicate that the maintaining activation of TRPM2 is not only important for the quenching OS, inflammation, and neurotoxicity in the TG neurons of mice with experimental migraine but also equally critical to the modulation of GTN-induced pain.
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Affiliation(s)
- Yener Yazğan
- Department of Neuroscience, Health Science Institute, Suleyman Demirel University, Isparta, Turkey
| | - Mustafa Nazıroğlu
- Department of Neuroscience, Health Science Institute, Suleyman Demirel University, Isparta, Turkey. .,Neuroscience Research Center, Suleyman Demirel University, Isparta, Turkey. .,Drug Discovery Unit, BSN Health, Analyses, Innovation, Consultancy, Organization, Agriculture and Industry Ltd, Isparta, Turkey. .,Department of Biophysics, Faculty of Medicine, Suleyman Demirel University, TR-32260, Isparta, Turkey.
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5
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Qi R, Kang Y, Li X, Zhang X, Han Y, Cai R, Gao Y, Qi Y. Forsythiasides-Rich Extract From Forsythiae Fructus Inhibits Mast Cell Degranulation by Enhancing Mitochondrial Ca 2+ Uptake. Front Pharmacol 2021; 12:696729. [PMID: 34194333 PMCID: PMC8237228 DOI: 10.3389/fphar.2021.696729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 06/02/2021] [Indexed: 11/13/2022] Open
Abstract
Mast cells (MCs) activated via IgE/FcεRI or MAS-related G protein coupled receptor (Mrgpr)-mediated pathway can release granules that play prominent roles in hypersensitivity reactions. Forsythiae Fructus, a well-known traditional Chinese medicine, has been clinically used for allergic diseases. Although previous studies indicated that Forsythiae Fructus extract inhibited compound 48/80-induced histamine release from MCs, its effect on IgE-dependent MC degranulation and possible underlying mechanisms remain to be explored. Herein, we prepared the forsythiasides-rich extract (FRE) and investigated its action on MC degranulation and explored its underlying mechanism. Our data showed that FRE could dampen IgE/FcεRI- and Mrgpr-mediated MC degranulation in vitro and in vivo. Mechanism study indicated that FRE decreased cytosolic Ca2+ (Ca2+[c]) level rapidly and reversibly. Moreover, FRE decreased Ca2+[c] of MCs independent of plasma membrane Ca2+-ATPase (PMCA), sarco/endoplasmic Ca2+-ATPase (SERCA) and Na+/Ca2+ exchanger (NCX). While, along with Ca2+[c] decrease, the increase of mitochondrial Ca2+ (Ca2+[m]) occurred simultaneously in FRE-treated RBL-2H3 cells. In the isolated mitochondria, FRE also promoted the subcellular organelle to uptake more extramitochondrial Ca2+. In conclusion, by increasing Ca2+[m] uptake, FRE decreases Ca2+[c] level to suppress MC degranulation. Our findings may provide theoretical support for the clinical application of Forsythiae Fructus on allergy and other MC-involved diseases.
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Affiliation(s)
- Ruijuan Qi
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Yuan Kang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Ximeng Li
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xiaoyu Zhang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Yixin Han
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Runlan Cai
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Yuan Gao
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Yun Qi
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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Gao Y, Zhang X, Li X, Qi R, Han Y, Kang Y, Cai R, Peng C, Qi Y. Aloe-emodin, a naturally occurring anthraquinone, is a highly potent mast cell stabilizer through activating mitochondrial calcium uniporter. Biochem Pharmacol 2021; 186:114476. [PMID: 33607072 DOI: 10.1016/j.bcp.2021.114476] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/09/2021] [Accepted: 02/10/2021] [Indexed: 01/07/2023]
Abstract
Mast cells play a fundamental role in immune system. Upon stimulation, they are activated via IgE dependent or independent pathway and then release granules which contain plenty of preformed constituents. Mast cell stabilizers are commonly used clinically for inhibiting the degranulation of mast cells. In the current study, we firstly identified aloe-emodin, a naturally occurring anthraquinone, was a prominent mast cell stabilizer. It could strikingly dampen IgE/FcεRI- and MAS-related G protein coupled receptor (Mrgpr)-mediated mast cell degranulation in vitro and in vivo. Mechanism study indicated that aloe-emodin rapidly and reversibly decreased cytosolic Ca2+ (Ca2+[c]) concentration through enhancing the mitochondrial Ca2+ (Ca2+[m]) uptake. After genetically silencing or pharmacologic inhibiting mitochondrial calcium uniporter (MCU), the effects of aloe-emodin on the Ca2+[c] level and mast cell degranulation were significantly weakened. In contrast to six clinical drugs with mast cell stabilizing properties (amlexanox, tranilast, ketotifen, cromolyn disodium salt, dexamethasone and pimecrolimus), aloe-emodin showed an impressive and potent inhibitory action on the mast cell degranulation. Collectively, aloe-emodin is a highly potent mast cell stabilizer. By directly activating MCU, it decreases Ca2+[c] level to suppress mast cell degranulation. Our study may provide a promising candidate for the treatment of mast cell activation-related diseases.
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Affiliation(s)
- Yuan Gao
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China
| | - Xiaoyu Zhang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China
| | - Ximeng Li
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China
| | - Ruijuan Qi
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China
| | - Yixin Han
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China
| | - Yuan Kang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China
| | - Runlan Cai
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China
| | - Cheng Peng
- Chengdu University of Traditional Chinese Medicine, Chengdu 610075, China.
| | - Yun Qi
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China.
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Gao Y, Hou R, Fei Q, Fang L, Han Y, Cai R, Peng C, Qi Y. The Three-Herb Formula Shuang-Huang-Lian stabilizes mast cells through activation of mitochondrial calcium uniporter. Sci Rep 2017; 7:38736. [PMID: 28045016 PMCID: PMC5206722 DOI: 10.1038/srep38736] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 11/14/2016] [Indexed: 12/31/2022] Open
Abstract
Mast cells (MCs) are key effector cells of IgE-FcεRI- or MrgprX2-mediated signaling event. Shuang-Huang-Lian (SHL), a herbal formula from Chinese Pharmacopoeia, has been clinically used in type I hypersensitivity. Our previous study demonstrated that SHL exerted a non-negligible effect on MC stabilization. Herein, we sought to elucidate the molecular mechanisms of the prominent anti-allergic ability of SHL. MrgprX2- and IgE-FcεRI-mediated MC activation in vitro and in vivo models were developed by using compound 48/80 (C48/80) and shrimp tropomyosin (ST), respectively. Our data showed that SHL markedly dampened C48/80- or ST-induced MC degranulation in vitro and in vivo. Mechanistic study indicated that cytosolic Ca2+ (Ca2+[c]) level decreased rapidly and sustainably after SHL treatment, and then returned to homeostasis when SHL was withdrawn. Moreover, SHL decreases Ca2+[c] levels mainly through enhancing the mitochondrial Ca2+ (Ca2+[m]) uptake. After genetically silencing or pharmacologic inhibiting mitochondrial calcium uniporter (MCU), the effect of SHL on the Ca2+[c] level and MC degranulation was significantly weakened. Simultaneously, the activation of SHL on Ca2+[m] uptake was completely lost. Collectively, by activating MCU, SHL decreases Ca2+[c] level to stabilize MCs, thus exerting a remarkable anti-allergic activity, which could have considerable influences on clinical practice and research.
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Affiliation(s)
- Yuan Gao
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, 100193, China.,Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
| | - Rui Hou
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, 100193, China
| | - Qiaoling Fei
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, 100193, China
| | - Lei Fang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, 100193, China
| | - Yixin Han
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, 100193, China
| | - Runlan Cai
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, 100193, China
| | - Cheng Peng
- Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
| | - Yun Qi
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, 100193, China
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8
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Chung MK, Campbell JN. Use of Capsaicin to Treat Pain: Mechanistic and Therapeutic Considerations. Pharmaceuticals (Basel) 2016; 9:ph9040066. [PMID: 27809268 PMCID: PMC5198041 DOI: 10.3390/ph9040066] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/25/2016] [Accepted: 10/27/2016] [Indexed: 12/31/2022] Open
Abstract
Capsaicin is the pungent ingredient of chili peppers and is approved as a topical treatment of neuropathic pain. The analgesia lasts for several months after a single treatment. Capsaicin selectively activates TRPV1, a Ca2+-permeable cationic ion channel that is enriched in the terminals of certain nociceptors. Activation is followed by a prolonged decreased response to noxious stimuli. Interest also exists in the use of injectable capsaicin as a treatment for focal pain conditions, such as arthritis and other musculoskeletal conditions. Recently injection of capsaicin showed therapeutic efficacy in patients with Morton’s neuroma, a painful foot condition associated with compression of one of the digital nerves. The relief of pain was associated with no change in tactile sensibility. Though injection evokes short term pain, the brief systemic exposure and potential to establish long term analgesia without other sensory changes creates an attractive clinical profile. Short-term and long-term effects arise from both functional and structural changes in nociceptive terminals. In this review, we discuss how local administration of capsaicin may induce ablation of nociceptive terminals and the clinical implications.
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Affiliation(s)
- Man-Kyo Chung
- Department of Neural and Pain Sciences, University of Maryland, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, Baltimore, MD 21201, USA.
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Calvo M, Sanz-Blasco S, Caballero E, Villalobos C, Núñez L. Susceptibility to excitotoxicity in aged hippocampal cultures and neuroprotection by non-steroidal anti-inflammatory drugs: role of mitochondrial calcium. J Neurochem 2015; 132:403-17. [DOI: 10.1111/jnc.13004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 01/20/2023]
Affiliation(s)
- María Calvo
- Instituto de Biología y Genética Molecular (IBGM); Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Valladolid; Valladolid Spain
| | - Sara Sanz-Blasco
- Instituto de Biología y Genética Molecular (IBGM); Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Valladolid; Valladolid Spain
| | - Erica Caballero
- Instituto de Biología y Genética Molecular (IBGM); Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Valladolid; Valladolid Spain
| | - Carlos Villalobos
- Instituto de Biología y Genética Molecular (IBGM); Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Valladolid; Valladolid Spain
| | - Lucía Núñez
- Instituto de Biología y Genética Molecular (IBGM); Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Valladolid; Valladolid Spain
- Departamento de Bioquímica y Biología Molecular y Fisiología; Universidad de Valladolid; Valladolid Spain
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Hogan QH, Sprick C, Guo Y, Mueller S, Bienengraeber M, Pan B, Wu HE. Divergent effects of painful nerve injury on mitochondrial Ca(2+) buffering in axotomized and adjacent sensory neurons. Brain Res 2014; 1589:112-25. [PMID: 25251590 DOI: 10.1016/j.brainres.2014.09.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 09/09/2014] [Accepted: 09/15/2014] [Indexed: 02/05/2023]
Abstract
Mitochondria critically regulate cytoplasmic Ca(2+) concentration ([Ca(2+)]c), but the effects of sensory neuron injury have not been examined. Using FCCP (1µM) to eliminate mitochondrial Ca(2+) uptake combined with oligomycin (10µM) to prevent ATP depletion, we first identified features of depolarization-induced neuronal [Ca(2+)]c transients that are sensitive to blockade of mitochondrial Ca(2+) buffering in order to assess mitochondrial contributions to [Ca(2+)]c regulation. This established the loss of a shoulder during the recovery of the depolarization (K(+))-induced transient, increased transient peak and area, and elevated shoulder level as evidence of diminished mitochondrial Ca(2+) buffering. We then examined transients in Control neurons and neurons from the 4th lumbar (L4) and 5th lumbar (L5) dorsal root ganglia after L5 spinal nerve ligation (SNL). The SNL L4 neurons showed decreased transient peak and area compared to control neurons, while the SNL L5 neurons showed increased shoulder level. Additionally, SNL L4 neurons developed shoulders following transients with lower peaks than Control neurons. Application of FCCP plus oligomycin elevated resting [Ca(2+)]c in SNL L4 neurons more than in Control neurons. Whereas application of FCCP plus oligomycin 2s after neuronal depolarization initiated mitochondrial Ca(2+) release in most Control and SNL L4 neurons, this usually failed to release mitochondrial Ca(2+) from SNL L5 neurons. For comparable cytoplasmic Ca(2+) loads, the releasable mitochondrial Ca(2+) in SNL L5 neurons was less than Control while it was increased in SNL L4 neurons. These findings show diminished mitochondrial Ca(2+) buffering in axotomized SNL L5 neurons but enhanced Ca(2+) buffering by neurons in adjacent SNL L4 neurons.
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Affiliation(s)
- Quinn H Hogan
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA; Zablocki VA Medical Center, 5000 W National Avenue, Milwaukee, WI 53295, USA
| | - Chelsea Sprick
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA
| | - Yuan Guo
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA
| | - Samantha Mueller
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA
| | - Martin Bienengraeber
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA; Department of Pharmacology and Toxicology, Medical College of Wisconsin, USA
| | - Bin Pan
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA
| | - Hsiang-En Wu
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA.
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11
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Kuroda H, Sobhan U, Sato M, Tsumura M, Ichinohe T, Tazaki M, Shibukawa Y. Sodium-calcium exchangers in rat trigeminal ganglion neurons. Mol Pain 2013; 9:22. [PMID: 23628073 PMCID: PMC3646678 DOI: 10.1186/1744-8069-9-22] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 04/19/2013] [Indexed: 01/10/2023] Open
Abstract
Background Noxious stimulation and nerve injury induce an increase in intracellular Ca2+ concentration ([Ca2+]i) via various receptors or ionic channels. While an increase in [Ca2+]i excites neurons, [Ca2+]i overload elicits cytotoxicity, resulting in cell death. Intracellular Ca2+ is essential for many signal transduction mechanisms, and its level is precisely regulated by the Ca2+ extrusion system in the plasma membrane, which includes the Na+-Ca2+ exchanger (NCX). It has been demonstrated that Ca2+-ATPase is the primary mechanism for removing [Ca2+]i following excitatory activity in trigeminal ganglion (TG) neurons; however, the role of NCXs in this process has yet to be clarified. The goal of this study was to examine the expression/localization of NCXs in TG neurons and to evaluate their functional properties. Results NCX isoforms (NCX1, NCX2, and NCX3) were expressed in primary cultured rat TG neurons. All the NCX isoforms were also expressed in A-, peptidergic C-, and non-peptidergic C-neurons, and located not only in the somata, dendrites, axons and perinuclear region, but also in axons innervating the dental pulp. Reverse NCX activity was clearly observed in TG neurons. The inactivation kinetics of voltage-dependent Na+ channels were prolonged by NCX inhibitors when [Ca2+]i in TG neurons was elevated beyond physiological levels. Conclusions Our results suggest that NCXs in TG neurons play an important role in regulating Ca2+-homeostasis and somatosensory information processing by functionally coupling with voltage-dependent Na+ channels.
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Affiliation(s)
- Hidetaka Kuroda
- Oral Health Science Center hrc8, Tokyo Dental College, Tokyo 261-8502, Japan
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12
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Hooper JS, Hadley SH, Mathews A, Taylor-Clark TE. Store-operated calcium entry in vagal sensory nerves is independent of Orai channels. Brain Res 2013; 1503:7-15. [PMID: 23399679 DOI: 10.1016/j.brainres.2013.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/26/2012] [Accepted: 02/02/2013] [Indexed: 11/30/2022]
Abstract
Vagal sensory nerves innervate the majority of visceral organs (e.g., heart, lungs, GI tract, etc) and their activation is critical for defensive and regulatory reflexes. Intracellular Ca(2+) is a key regulator of neuronal excitability and is largely controlled by the Ca(2+) stores of the endoplasmic reticulum. In other cell types store-operated channels (SOC) have been shown to contribute to the homeostatic control of intracellular Ca(2+). Here, using Ca(2+) imaging, we have shown that ER depletion in vagal sensory neurons (using thapsigargin or caffeine) in the absence of extracellular Ca(2+) evoked Ca(2+) influx upon re-introduction of Ca(2+) into the extracellular buffer. This store-operated Ca(2+) entry (SOCE) was observed in approximately 25-40% of vagal neurons, equally distributed among nociceptive and non-nociceptive sensory subtypes. SOCE was blocked by Gd(3+) but not by the Orai channel blocker SKF96365. We found Orai channel mRNA in extracts from whole vagal ganglia, but when using single cell RT-PCR analysis we found only 3 out of 34 neurons expressed Orai channel mRNA, indicating that Orai channel expression in the vagal ganglia was likely derived from non-neuronal cell types. Confocal microscopy of vagal neurons in 3 day cultures demonstrated rich ER tracker fluorescence throughout axonal and neurite structures and ER store depletion (thapsigargin) evoked Ca(2+) transients from these structures. However, no SOCE could be detected in the axonal/neurite structures of vagal neurons. We conclude that SOCE occurs in vagal sensory neuronal cell bodies through non-Orai mechanisms but is absent at nerve terminals.
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Affiliation(s)
- Justin Shane Hooper
- Department of Molecular Pharmacology & Physiology, College of Medicine, University of South Florida, 12901 Bruce B Downs Blvd, Tampa, USA.
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Shutov LP, Kim MS, Houlihan PR, Medvedeva YV, Usachev YM. Mitochondria and plasma membrane Ca2+-ATPase control presynaptic Ca2+ clearance in capsaicin-sensitive rat sensory neurons. J Physiol 2013; 591:2443-62. [PMID: 23381900 DOI: 10.1113/jphysiol.2012.249219] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The central processes of primary nociceptors form synaptic connections with the second-order nociceptive neurons located in the dorsal horn of the spinal cord. These synapses gate the flow of nociceptive information from the periphery to the CNS, and plasticity at these synapses contributes to centrally mediated hyperalgesia and allodynia. Although exocytosis and synaptic plasticity are controlled by Ca(2+) at the release sites, the mechanisms underlying presynaptic Ca(2+) signalling at the nociceptive synapses are not well characterized. We examined the presynaptic mechanisms regulating Ca(2+) clearance following electrical stimulation in capsaicin-sensitive nociceptors using a dorsal root ganglion (DRG)/spinal cord neuron co-culture system. Cytosolic Ca(2+) concentration ([Ca(2+)]i) recovery following electrical stimulation was well approximated by a monoexponential function with a ∼2 s. Inhibition of sarco-endoplasmic reticulum Ca(2+)-ATPase did not affect presynaptic [Ca(2+)]i recovery, and blocking plasmalemmal Na(+)/Ca(2+) exchange produced only a small reduction in the rate of [Ca(2+)]i recovery (∼12%) that was independent of intracellular K(+). However, [Ca(2+)]i recovery in presynaptic boutons strongly depended on the plasma membrane Ca(2+)-ATPase (PMCA) and mitochondria that accounted for ∼47 and 40%, respectively, of presynaptic Ca(2+) clearance. Measurements using a mitochondria-targeted Ca(2+) indicator, mtPericam, demonstrated that presynaptic mitochondria accumulated Ca(2+) in response to electrical stimulation. Quantitative analysis revealed that the mitochondrial Ca(2+) uptake is highly sensitive to presynaptic [Ca(2+)]i elevations, and occurs at [Ca(2+)]i levels as low as ∼200-300 nm. Using RT-PCR, we detected expression of several putative mitochondrial Ca(2+) transporters in DRG, such as MCU, Letm1 and NCLX. Collectively, this work identifies PMCA and mitochondria as the major regulators of presynaptic Ca(2+) signalling at the first sensory synapse, and underlines the high sensitivity of the mitochondrial Ca(2+) uniporter in neurons to cytosolic Ca(2+).
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Affiliation(s)
- Leonid P Shutov
- Y. M. Usachev: Department of Pharmacology, University of Iowa Carver College of Medicine, 2-340F BSB, 51 Newton Road, Iowa City, IA 52242, USA
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Duncan C, Mueller S, Simon E, Renger JJ, Uebele VN, Hogan QH, Wu HE. Painful nerve injury decreases sarco-endoplasmic reticulum Ca²⁺-ATPase activity in axotomized sensory neurons. Neuroscience 2012; 231:247-57. [PMID: 23219911 DOI: 10.1016/j.neuroscience.2012.11.055] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 11/28/2012] [Accepted: 11/29/2012] [Indexed: 12/15/2022]
Abstract
The sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) is a critical pathway by which sensory neurons sequester cytosolic Ca(2+) and thereby maintain intracellular Ca(2+) homeostasis. We have previously demonstrated decreased intraluminal endoplasmic reticulum Ca(2+) concentration in traumatized sensory neurons. Here we examine SERCA function in dissociated sensory neurons using Fura-2 fluorometry. Blocking SERCA with thapsigargin (1 μM) increased resting [Ca(2+)](c) and prolonged recovery (τ) from transients induced by neuronal activation (elevated bath K(+)), demonstrating SERCA contributes to control of resting [Ca(2+)](c) and recovery from transient [Ca(2+)](c) elevation. To evaluate SERCA in isolation, plasma membrane Ca(2+) ATPase was blocked with pH 8.8 bath solution and mitochondrial buffering was avoided by keeping transients small (≤ 400 nM). Neurons axotomized by spinal nerve ligation (SNL) showed a slowed rate of transient recovery compared to control neurons, representing diminished SERCA function, whereas neighboring non-axotomized neurons from SNL animals were unaffected. Injury did not affect SERCA function in large neurons. Repeated depolarization prolonged transient recovery, showing that neuronal activation inhibits SERCA function. These findings suggest that injury-induced loss of SERCA function in small sensory neurons may contribute to the generation of pain following peripheral nerve injury.
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Affiliation(s)
- C Duncan
- Medical College of Wisconsin, Department of Anesthesiology, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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15
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Lebovitz EE, Keller JM, Kominsky H, Kaszas K, Maric D, Iadarola MJ. Positive allosteric modulation of TRPV1 as a novel analgesic mechanism. Mol Pain 2012; 8:70. [PMID: 22998799 PMCID: PMC3556054 DOI: 10.1186/1744-8069-8-70] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 09/11/2012] [Indexed: 12/21/2022] Open
Abstract
Background The prevalence of long-term opiate use in treating chronic non-cancer pain is increasing, and prescription opioid abuse and dependence are a major public health concern. To explore alternatives to opioid-based analgesia, the present study investigates a novel allosteric pharmacological approach operating through the cation channel TRPV1. This channel is highly expressed in subpopulations of primary afferent unmyelinated C- and lightly-myelinated Aδ-fibers that detect low and high rates of noxious heating, respectively, and it is also activated by vanilloid agonists and low pH. Sufficient doses of exogenous vanilloid agonists, such as capsaicin or resiniferatoxin, can inactivate/deactivate primary afferent endings due to calcium overload, and we hypothesized that positive allosteric modulation of agonist-activated TRPV1 could produce a selective, temporary inactivation of nociceptive nerve terminals in vivo. We previously identified MRS1477, a 1,4-dihydropyridine that potentiates vanilloid and pH activation of TRPV1 in vitro, but displays no detectable intrinsic agonist activity of its own. To study the in vivo effects of MRS1477, we injected the hind paws of rats with a non-deactivating dose of capsaicin, MRS1477, or the combination. An infrared diode laser was used to stimulate TRPV1-expressing nerve terminals and the latency and intensity of paw withdrawal responses were recorded. qRT-PCR and immunohistochemistry were performed on dorsal root ganglia to examine changes in gene expression and the cellular specificity of such changes following treatment. Results Withdrawal responses of the capsaicin-only or MRS1477-only treated paws were not significantly different from the untreated, contralateral paws. However, rats treated with the combination of capsaicin and MRS1477 exhibited increased withdrawal latency and decreased response intensity consistent with agonist potentiation and inactivation or lesion of TRPV1-containing nerve terminals. The loss of nerve endings was manifested by an increase in levels of axotomy markers assessed by qRT-PCR and colocalization of ATF3 in TRPV1+ cells visualized via immunohistochemistry. Conclusions The present observations suggest a novel, non-narcotic, selective, long-lasting TRPV1-based approach for analgesia that may be effective in acute, persistent, or chronic pain disorders.
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Affiliation(s)
- Evan E Lebovitz
- Neurobiology and Pain Therapeutics Section, Laboratory Of Sensory Biology, NIDCR, NIH, Bldg 49 Rm 1C2049 Convent Dr, Bethesda, MD 20892, USA
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Gemes G, Oyster KD, Pan B, Wu HE, Bangaru MLY, Tang Q, Hogan QH. Painful nerve injury increases plasma membrane Ca2+-ATPase activity in axotomized sensory neurons. Mol Pain 2012; 8:46. [PMID: 22713297 PMCID: PMC3481352 DOI: 10.1186/1744-8069-8-46] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 06/13/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The plasma membrane Ca2+-ATPase (PMCA) is the principal means by which sensory neurons expel Ca2+ and thereby regulate the concentration of cytoplasmic Ca2+ and the processes controlled by this critical second messenger. We have previously found that painful nerve injury decreases resting cytoplasmic Ca2+ levels and activity-induced cytoplasmic Ca2+ accumulation in axotomized sensory neurons. Here we examine the contribution of PMCA after nerve injury in a rat model of neuropathic pain. RESULTS PMCA function was isolated in dissociated sensory neurons by blocking intracellular Ca2+ sequestration with thapsigargin, and cytoplasmic Ca2+ concentration was recorded with Fura-2 fluorometry. Compared to control neurons, the rate at which depolarization-induced Ca2+ transients resolved was increased in axotomized neurons after spinal nerve ligation, indicating accelerated PMCA function. Electrophysiological recordings showed that blockade of PMCA by vanadate prolonged the action potential afterhyperpolarization, and also decreased the rate at which neurons could fire repetitively. CONCLUSION We found that PMCA function is elevated in axotomized sensory neurons, which contributes to neuronal hyperexcitability. Accelerated PMCA function in the primary sensory neuron may contribute to the generation of neuropathic pain, and thus its modulation could provide a new pathway for peripheral treatment of post-traumatic neuropathic pain.
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Affiliation(s)
- Geza Gemes
- Medical College of Wisconsin, Department of Anesthesiology, Milwaukee, WI 53226, USA
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Fang XF, Cui ZJ. The anti-botulism triterpenoid toosendanin elicits calcium increase and exocytosis in rat sensory neurons. Cell Mol Neurobiol 2011; 31:1151-62. [PMID: 21656151 DOI: 10.1007/s10571-011-9716-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 05/20/2011] [Indexed: 02/07/2023]
Abstract
Toosendanin, a triterpenoid from Melia toosendan Sieb et Zucc, has been found before to be an effective anti-botulism agent, with a bi-phasic effect at both motor nerve endings and central synapse: an initial facilitation followed by prolonged depression. Initial facilitation may be due to activation of voltage-dependent calcium channels plus inhibition of potassium channels, but the depression is not fully understood. Toosendanin has no effect on intracellular calcium or secretion in the non-excitable pancreatic acinar cells, ruling out general toosendanin inhibition of exocytosis. In this study, toosendanin effects on sensory neurons isolated from rat nodose ganglia were investigated. It was found that toosendanin stimulated increases in cytosolic calcium and neuronal exocytosis dose dependently. Experiments with membrane potential indicator bis-(1,3-dibutylbarbituric acid)trimethine oxonol found that toosendanin hyperpolarized capsaicin-insensitive but depolarized capsaicin-sensitive neurons; high potassium-induced calcium increase was much smaller in hyperpolarizing neurons than in depolarizing neurons, whereas no difference was found for potassium-induced depolarization in these two types of neurons. In neurons showing spontaneous calcium oscillations, toosendanin increased the oscillatory amplitude but not frequency. Toosendanin-induced calcium increase was decreased in calcium-free buffer, by nifedipine, and by transient receptor potential vanilloid 1 (TRPV1) antagonist capsazepine. Simultaneous measurements of cytosolic and endoplasmic reticulum (ER) calcium showed an increase in cytosolic but a decrease in ER calcium, indicating that toosendanin triggered ER calcium release. These data together indicate that toosendanin modulates sensory neurons, but had opposite effects on membrane potential depending on the presence or absence of capsaicin receptor/TRPV 1 channel.
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Affiliation(s)
- Xiao Feng Fang
- Institute of Cell Biology, Beijing Normal University, Beijing 100875, China
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Poburko D, Santo-Domingo J, Demaurex N. Dynamic regulation of the mitochondrial proton gradient during cytosolic calcium elevations. J Biol Chem 2011; 286:11672-84. [PMID: 21224385 PMCID: PMC3064219 DOI: 10.1074/jbc.m110.159962] [Citation(s) in RCA: 243] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Mitochondria extrude protons across their inner membrane to generate the mitochondrial membrane potential (ΔΨm) and pH gradient (ΔpHm) that both power ATP synthesis. Mitochondrial uptake and efflux of many ions and metabolites are driven exclusively by ΔpHm, whose in situ regulation is poorly characterized. Here, we report the first dynamic measurements of ΔpHm in living cells, using a mitochondrially targeted, pH-sensitive YFP (SypHer) combined with a cytosolic pH indicator (5-(and 6)-carboxy-SNARF-1). The resting matrix pH (∼7.6) and ΔpHm (∼0.45) of HeLa cells at 37 °C were lower than previously reported. Unexpectedly, mitochondrial pH and ΔpHm decreased during cytosolic Ca2+ elevations. The drop in matrix pH was due to cytosolic acid generated by plasma membrane Ca2+-ATPases and transmitted to mitochondria by Pi/H+ symport and K+/H+ exchange, whereas the decrease in ΔpHm reflected the low H+-buffering power of mitochondria (∼5 mm, pH 7.8) compared with the cytosol (∼20 mm, pH 7.4). Upon agonist washout and restoration of cytosolic Ca2+ and pH, mitochondria alkalinized and ΔpHm increased. In permeabilized cells, a decrease in bath pH from 7.4 to 7.2 rapidly decreased mitochondrial pH, whereas the addition of 10 μm Ca2+ caused a delayed and smaller alkalinization. These findings indicate that the mitochondrial matrix pH and ΔpHm are regulated by opposing Ca2+-dependent processes of stimulated mitochondrial respiration and cytosolic acidification.
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Affiliation(s)
- Damon Poburko
- Department of Cell Physiology and Metabolism, University of Geneva Medical School, Geneva, Switzerland
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Hwang SM, Koo NY, Jin M, Davies AJ, Chun GS, Choi SY, Kim JS, Park K. Intracellular acidification is associated with changes in free cytosolic calcium and inhibition of action potentials in rat trigeminal ganglion. J Biol Chem 2010; 286:1719-29. [PMID: 21068392 DOI: 10.1074/jbc.m109.090951] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The effect of intracellular acidification and subsequent pH recovery in sensory neurons has not been well characterized. We have studied the mechanisms underlying Ca(2+)-induced acidification and subsequent recovery of intracellular pH (pH(i)) in rat trigeminal ganglion neurons and report their effects on neuronal excitability. Glutamate (500 μM) and capsaicin (1 μM) increased intracellular Ca(2+) concentration ([Ca(2+)](i)) with a following decrease in pH(i). The recovery of [Ca(2+)](i) to the prestimulus level was inhibited by LaCl(3) (1 mM) and o-vanadate (10 mM), a plasma membrane Ca(2+)/ATPase (PMCA) inhibitor. Removal of extracellular Ca(2+) also completely inhibited the acidification induced by capsaicin. TRPV1 was expressed only in small and medium sized trigeminal ganglion neurons. mRNAs for Na(+)/H(+) exchanger type 1 (NHE1), pancreatic Na(+)-HCO(3)(-) cotransporter type 1 (pNBC1), NBC3, NBC4, and PMCA types 1-3 were detected by RT-PCR. pH(i) recovery was significantly inhibited by pretreatment with NHE1 or pNBC1 siRNA. We found that the frequency of action potentials (APs) was dependent on pH(i). Application of the NHE1 inhibitor 5'-(N-ethyl-N-isopropyl) amiloride (5 μM) or the pNBC1 inhibitor 4',4'-di-isothiocyanostilbene-2',2'-sulfonic acid (500 μM) delayed pH(i) recovery and decreased AP frequency. Simultaneous application of 5'-(N-ethyl-N-isopropyl) amiloride and 4',4'-di-isothiocyanostilbene-2',2'-sulfonic acid almost completely inhibited APs. In summary, our results demonstrate that the rise in [Ca(2+)](i) in sensory neurons by glutamate and capsaicin causes intracellular acidification by activation of PMCA type 3, that the pH(i) recovery from acidification is mediated by membrane transporters NHE1 and pNBC1 specifically, and that the activity of these transporters has direct consequences for neuronal excitability.
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Affiliation(s)
- Sung-Min Hwang
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Yeongeondong 28, Chongnoku, Seoul 110-749, Korea
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Abstract
The fundamental role of calcium ions (Ca(2+)) in an excitable tissue, the frog heart, was first demonstrated in a series of classical reports by Sydney Ringer in the latter part of the nineteenth century (1882a, b; 1893a, b). Even so, nearly a century elapsed before it was proven that Ca(2+) regulated the excitability of primary sensory neurons. In this chapter we review the sites and mechanisms whereby internal and external Ca(2+) can directly or indirectly alter the excitability of primary sensory neurons: excitability changes being manifested typically by variations in shape of the action potential or the pattern of its discharge.
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Kang SH, Carl A, McHugh JM, Goff HR, Kenyon JL. Roles of mitochondria and temperature in the control of intracellular calcium in adult rat sensory neurons. Cell Calcium 2007; 43:388-404. [PMID: 17716728 PMCID: PMC2409216 DOI: 10.1016/j.ceca.2007.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Revised: 07/08/2007] [Accepted: 07/15/2007] [Indexed: 11/17/2022]
Abstract
We recorded Ca2+ current and intracellular Ca2+ ([Ca2+](i)) in isolated adult rat dorsal root ganglion (DRG) neurons at 20 and 30 degrees C. In neurons bathed in tetraethylammonium and dialyzed with cesium, warming reduced resting [Ca2+](i) from 87 to 49 nM and the time constant of the decay of [Ca2+](i) transients (tau(r)) from 1.3 to 0.99s (Q(10)=1.4). The Buffer Index, the ratio between Ca2+ influx and Delta[Ca2+](i) (f I(ca)d(t)/Delta[Ca2+]i) , increased two- to threefold with warming. Neither inhibition of the plasma membrane Ca2+ -ATPase by intracellular sodium orthovanadate nor inhibition of Ca2+ uptake by the endoplasmic reticulum by thapsigargin plus ryanodine were necessary for the effects of warming on these parameters. In contrast, inhibition of the mitochondrial Ca2+ uniporter by intracellular ruthenium red largely reversed the effects of warming. Carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP, 500 nM) increased resting [Ca2+](i) at 30 degrees C. Ten millimolar intracellular sodium prolonged the recovery of [Ca2+](i) transients to 10-40s. This effect was reversed by an inhibitor of mitochondrial Na(+)/Ca2+ -exchange (CGP 37157, 10 microM). Thus, mitochondrial Ca2+ uptake is necessary for the temperature-dependent increase in Ca2+ buffering and mitochondrial Ca2+ fluxes contribute to the control of [Ca2+](i) between 50 and 150 nM at 30 degrees C.
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Affiliation(s)
- S H Kang
- Department of Physiology & Cell Biology/MS 352, University of Nevada School of Medicine, Reno, NV 89557, USA
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22
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Moreira THV, Gover TD, Weinreich D. Electrophysiological properties and chemosensitivity of acutely dissociated trigeminal somata innervating the cornea. Neuroscience 2007; 148:766-74. [PMID: 17706884 PMCID: PMC3390199 DOI: 10.1016/j.neuroscience.2007.03.056] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Revised: 03/02/2007] [Accepted: 04/04/2007] [Indexed: 11/25/2022]
Abstract
Adult rat sensory trigeminal ganglion neurons innervating the cornea (cTGNs) were isolated and identified following retrograde dye labeling with FM1-43. Using standard whole-cell patch clamp recording techniques, cTGNs could be subdivided by their action potential (AP) duration. Fast cTGNs had AP durations <1 ms (40%) while slow cTGNs had AP durations >1 ms and an inflection on the repolarization phase of the AP. With the exception of membrane input resistance, the passive membrane properties of fast cTGNs were different from those of slow cTGNs (capacitance: 61+/-4.5 pF vs. 42+/-2.6 pF, resting membrane potential: -59+/-0.7 mV vs. -53+/-0.9 mV, for fast and slow cTGNs respectively). Active membrane properties also differed between fast and slow cTGNs. Slow cTGNs had a higher AP threshold (-25+/-1.6 mV vs. -38+/-0.8 mV), a larger rheobase (14+/-1.9 pA/pF vs. 6.8+/-1.0 pA/pF), and a smaller AP undershoot (-56+/-1.7 mV vs. -67+/-2.5 mV). The AP overshoot, however was similar between the two types of neurons (46+/-3.1 mV vs. 48+/-4 mV). Slow cTGNs were depolarized by capsaicin (1 microM, 80%) and 60% of their APs were blocked by tetrodotoxin (TTX) (100 nM). Fast cTGNs were unaffected by capsaicin and 100% of their APs were blocked by TTX. Similarly, cTGNs were also heterogeneous with respect to their responses to exogenous ATP and 5-HT. The current work shows that cTGNs have distinctive electrophysiological properties and chemosensitivity profiles. These characteristics may mirror the distinct properties of corneal sensory nerve terminals. The availability of isolated identified cTGNs constitutes a tractable model system to investigate the biophysical and pharmacological properties of corneal sensory nerve terminals.
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Affiliation(s)
- Thaís Helena Veiga Moreira
- Department of Pharmacology and Experimental Therapeutics, University of Maryland, School of Medicine, Baltimore, MD, USA
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Tony D Gover
- Department of Pharmacology and Experimental Therapeutics, University of Maryland, School of Medicine, Baltimore, MD, USA
| | - Daniel Weinreich
- Department of Pharmacology and Experimental Therapeutics, University of Maryland, School of Medicine, Baltimore, MD, USA
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