1
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Wang H, Zhang Y, Shi Z, Pang H, Jia L, Feng H. Extracellular ATP is involved in regulating Arabidopsis seed germination. PLANTA 2022; 255:66. [PMID: 35152326 DOI: 10.1007/s00425-022-03839-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
Extracellular ATP level induced a transient increase during germination of Arabidopsis seeds, and extracellular ATP could negatively regulate the seed germination by its receptor, DORN1. Extracellular ATP (exATP) acts as a signal molecule for regulating growth, development, and responses of plants to external environments. In this study, we investigated the possible involvement of exATP in regulating the seed germination of Arabidopsis thaliana. Treatments of Arabidopsis seeds with exogenous ATP delayed seed germination, suggesting that exATP could be a repressor for seed germination. During the germination of Arabidopsis seeds, the exATP level of the seeds presented a transient increase. When exogenous application of the glucose-hexokinase system effectively decreased the exATP level of the Arabidopsis seeds during germination, the percentage of germination was significantly enhanced, while the products of ATP hydrolysis had no effects on the germination. Further studies showed that the seeds of dorn 1-3 mutant plants (mutation in exATP receptor) showed a higher germination percentage, compared to the seeds of wide type (WT) plants. In addition, the dorn 1-3 mutant seeds were less sensitive to the delay-effect of exogenous ATP on seed germination than the WT seeds. The dorn 1-3 mutant seeds presented a higher GA (gibberellin) content, lower ABA (abscisic acid) content, and lower ratio of ABA/GA contents before the imbibition, compared to the WT seeds. The regulation of seed germination by exATP was dependent on the external temperature. These data suggest that exATP is involved in regulating Arabidopsis seed germination.
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Affiliation(s)
- Hanqi Wang
- College of Life Science, Northwest Normal University, Lanzhou, 730070, Gansu, China
| | - Yuejing Zhang
- College of Life Science, Northwest Normal University, Lanzhou, 730070, Gansu, China
| | - Zhenzhen Shi
- College of Life Science, Northwest Normal University, Lanzhou, 730070, Gansu, China
| | - Hailong Pang
- College of Life Science, Northwest Normal University, Lanzhou, 730070, Gansu, China
| | - Lingyun Jia
- College of Life Science, Northwest Normal University, Lanzhou, 730070, Gansu, China
| | - Hanqing Feng
- College of Life Science, Northwest Normal University, Lanzhou, 730070, Gansu, China.
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2
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Heinrich UR, Meuser R, Ernst BP, Schmidtmann I, Dietrich D, Stauber RH, Strieth S. Regulation of Endothelial Nitric Oxide Synthase in the Reticular Lamina of the Organ of Corti by a Nitric Oxide Donor. J Histochem Cytochem 2021; 69:731-739. [PMID: 34666550 DOI: 10.1369/00221554211054642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the vertebrate cochlea, the reticular lamina seals the organ of Corti against the endolymph filled scala media. After noise exposure, fast alterations in the endothelial nitric oxide synthase (eNOS) expression level were identified in this cochlear structure. Minor amounts of nitric oxide (NO) produced by eNOS or applied by NO donors such as S-nitroso-N-acetyl-penicillamine (SNAP) might protect this vulnerable part of the organ of Corti, on the line of gap junctions of supporting cells and cochlear microcirculation. In n=5 anesthetized guinea pigs, SNAP was intravenously applied in two concentrations. Six untreated animals served as controls. The cochleae were removed and prepared for immunoelectron microscopy using specific gold-labeled anti-eNOS antibodies. The density of the gold particles was quantified for seven cellular regions in the reticular lamina at the ultrastructural level. Following SNAP application, a significant increase in eNOS expression (+176%) was detected compared with controls (p=0.012). The increase occurred mainly in actin-rich cuticular structures and the prominent microtubules bundles. Correlation analysis revealed three clear and five moderate cellular associations for controls, whereas only one clear and one moderate after SNAP application. Thus, application of the NO donor SNAP resulted in an increase in eNOS expression in distinct regions of the reticular lamina.
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Affiliation(s)
| | - Regina Meuser
- Institute for Medical Biometry, Epidemiology and Informatics
| | - Benjamin Philipp Ernst
- University Medical Center Mainz, Mainz, Germany, and Department of Otorhinolaryngology, University Medical Center Bonn (UKB), Bonn, Germany
| | | | - Dimo Dietrich
- University Medical Center Mainz, Mainz, Germany, and Department of Otorhinolaryngology, University Medical Center Bonn (UKB), Bonn, Germany
| | | | - Sebastian Strieth
- University Medical Center Mainz, Mainz, Germany, and Department of Otorhinolaryngology, University Medical Center Bonn (UKB), Bonn, Germany
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3
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Kitcher SR, Pederson AM, Weisz CJC. Diverse identities and sites of action of cochlear neurotransmitters. Hear Res 2021; 419:108278. [PMID: 34108087 DOI: 10.1016/j.heares.2021.108278] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 04/30/2021] [Accepted: 05/18/2021] [Indexed: 11/18/2022]
Abstract
Accurate encoding of acoustic stimuli requires temporally precise responses to sound integrated with cellular mechanisms that encode the complexity of stimuli over varying timescales and orders of magnitude of intensity. Sound in mammals is initially encoded in the cochlea, the peripheral hearing organ, which contains functionally specialized cells (including hair cells, afferent and efferent neurons, and a multitude of supporting cells) to allow faithful acoustic perception. To accomplish the demanding physiological requirements of hearing, the cochlea has developed synaptic arrangements that operate over different timescales, with varied strengths, and with the ability to adjust function in dynamic hearing conditions. Multiple neurotransmitters interact to support the precision and complexity of hearing. Here, we review the location of release, action, and function of neurotransmitters in the mammalian cochlea with an emphasis on recent work describing the complexity of signaling.
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Affiliation(s)
- Siân R Kitcher
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States
| | - Alia M Pederson
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States
| | - Catherine J C Weisz
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States.
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4
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Marchetta P, Rüttiger L, Hobbs AJ, Singer W, Knipper M. The role of cGMP signalling in auditory processing in health and disease. Br J Pharmacol 2021; 179:2378-2393. [PMID: 33768519 DOI: 10.1111/bph.15455] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/10/2021] [Accepted: 03/17/2021] [Indexed: 11/29/2022] Open
Abstract
cGMP is generated by the cGMP-forming guanylyl cyclases (GCs), the intracellular nitric oxide (NO)-sensitive (soluble) guanylyl cyclase (sGC) and transmembrane GC (e.g. GC-A and GC-B). In summarizing the particular role of cGMP signalling for hearing, we show that GC generally do not interfere significantly with basic hearing function but rather sustain a healthy state for proper temporal coding, fast discrimination and adjustments during injury. sGC is critical for the integrity of the first synapse in the ascending auditory pathway, the inner hair cell synapse. GC-A promotes hair cell stability under stressful conditions such as acoustic trauma or ageing. GC-B plays a role in the development of efferent feed-back and gain control. Regarding the crucial role hearing has for language development, speech discrimination and cognitive brain functions, differential pharmaceutical targeting of GCs offers therapeutic promise for the restoration of hearing.
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Affiliation(s)
- Philine Marchetta
- Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Lukas Rüttiger
- Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Adrian J Hobbs
- William Harvey Research Institute, Barts & The London School of Medicine & Dentistry, Queen Mary University of London, London, UK
| | - Wibke Singer
- Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Marlies Knipper
- Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
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5
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Kopp-Scheinpflug C, Forsythe ID. Nitric Oxide Signaling in the Auditory Pathway. Front Neural Circuits 2021; 15:759342. [PMID: 34712124 PMCID: PMC8546346 DOI: 10.3389/fncir.2021.759342] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 09/23/2021] [Indexed: 01/12/2023] Open
Abstract
Nitric oxide (NO) is of fundamental importance in regulating immune, cardiovascular, reproductive, neuromuscular, and nervous system function. It is rapidly synthesized and cannot be confined, it is highly reactive, so its lifetime is measured in seconds. These distinctive properties (contrasting with classical neurotransmitters and neuromodulators) give rise to the concept of NO as a "volume transmitter," where it is generated from an active source, diffuses to interact with proteins and receptors within a sphere of influence or volume, but limited in distance and time by its short half-life. In the auditory system, the neuronal NO-synthetizing enzyme, nNOS, is highly expressed and tightly coupled to postsynaptic calcium influx at excitatory synapses. This provides a powerful activity-dependent control of postsynaptic intrinsic excitability via cGMP generation, protein kinase G activation and modulation of voltage-gated conductances. NO may also regulate vesicle mobility via retrograde signaling. This Mini Review focuses on the auditory system, but highlights general mechanisms by which NO mediates neuronal intrinsic plasticity and synaptic transmission. The dependence of NO generation on synaptic and sound-evoked activity has important local modulatory actions and NO serves as a "volume transmitter" in the auditory brainstem. It also has potentially destructive consequences during intense activity or on spill-over from other NO sources during pathological conditions, when aberrant signaling may interfere with the precisely timed and tonotopically organized auditory system.
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Affiliation(s)
- Conny Kopp-Scheinpflug
- Neurobiology Laboratory, Division of Neurobiology, Faculty of Biology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Ian D Forsythe
- Auditory Neurophysiology Laboratory, Department of Neuroscience, Psychology and Behaviour, College of Life Sciences, University of Leicester, Leicester, United Kingdom
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6
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Vyas P, Wu JS, Jimenez A, Glowatzki E, Fuchs PA. Characterization of transgenic mouse lines for labeling type I and type II afferent neurons in the cochlea. Sci Rep 2019; 9:5549. [PMID: 30944354 PMCID: PMC6447598 DOI: 10.1038/s41598-019-41770-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 03/14/2019] [Indexed: 11/09/2022] Open
Abstract
The cochlea is innervated by type I and type II afferent neurons. Type I afferents are myelinated, larger diameter neurons that send a single dendrite to contact a single inner hair cell, whereas unmyelinated type II afferents are fewer in number and receive input from many outer hair cells. This strikingly differentiated innervation pattern strongly suggests specialized functions. Those functions could be investigated with specific genetic markers that enable labeling and manipulating each afferent class without significantly affecting the other. Here three mouse models were characterized and tested for specific labeling of either type I or type II cochlear afferents. Nos1CreER mice showed selective labeling of type I afferent fibers, Slc6a4-GFP mice labeled type II fibers with a slight preference for the apical cochlea, and Drd2-Cre mice selectively labeled type II afferent neurons nearer the cochlear base. In conjunction with the Th2A-CreER and CGRPα-EGFP lines described previously for labeling type II fibers, the mouse lines reported here comprise a promising toolkit for genetic manipulations of type I and type II cochlear afferent fibers.
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Affiliation(s)
- Pankhuri Vyas
- The Center for Hearing and Balance, Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Jingjing Sherry Wu
- The Center for Hearing and Balance, Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Adrian Jimenez
- The Center for Hearing and Balance, Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Elisabeth Glowatzki
- The Center for Hearing and Balance, Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
| | - Paul Albert Fuchs
- The Center for Hearing and Balance, Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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Wang L, Feng Y, Yan D, Qin L, Grati M, Mittal R, Li T, Sundhari AK, Liu Y, Chapagain P, Blanton SH, Liao S, Liu X. A dominant variant in the PDE1C gene is associated with nonsyndromic hearing loss. Hum Genet 2018; 137:437-446. [PMID: 29860631 PMCID: PMC6560636 DOI: 10.1007/s00439-018-1895-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 05/26/2018] [Indexed: 01/02/2023]
Abstract
Identification of genes with variants causing non-syndromic hearing loss (NSHL) is challenging due to genetic heterogeneity. The difficulty is compounded by technical limitations that in the past prevented comprehensive gene identification. Recent advances in technology, using targeted capture and next-generation sequencing (NGS), is changing the face of gene identification and making it possible to rapidly and cost-effectively sequence the whole human exome. Here, we characterize a five-generation Chinese family with progressive, postlingual autosomal dominant nonsyndromic hearing loss (ADNSHL). By combining population-specific mutation arrays, targeted deafness genes panel, whole exome sequencing (WES), we identified PDE1C (Phosphodiesterase 1C) c.958G>T (p.A320S) as the disease-associated variant. Structural modeling insights into p.A320S strongly suggest that the sequence alteration will likely affect the substrate-binding pocket of PDE1C. By whole-mount immunofluorescence on postnatal day 3 mouse cochlea, we show its expression in outer (OHC) and inner (IHC) hair cells cytosol co-localizing with Lamp-1 in lysosomes. Furthermore, we provide evidence that the variant alters the PDE1C hydrolytic activity for both cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Collectively, our findings indicate that the c.958G>T variant in PDE1C may disrupt the cross talk between cGMP-signaling and cAMP pathways in Ca2+ homeostasis.
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Affiliation(s)
- Li Wang
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
| | - Yong Feng
- Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, China
| | - Denise Yan
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
| | - Litao Qin
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - M'hamed Grati
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
- Laboratory of Cell Structure and Dynamics, NIDCD, NIH, Bethesda, MD, 20892, USA
| | - Rahul Mittal
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
| | - Tao Li
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Abhiraami Kannan Sundhari
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
| | - Yalan Liu
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
| | - Prem Chapagain
- Department of Physics, Florida International University, Miami, FL, USA
- Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Susan H Blanton
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Shixiu Liao
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Xuezhong Liu
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA.
- Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, China.
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
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8
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Fitzakerley JL, Trachte GJ. Genetics of guanylyl cyclase pathways in the cochlea and their influence on hearing. Physiol Genomics 2018; 50:780-806. [PMID: 29958079 DOI: 10.1152/physiolgenomics.00056.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Although hearing loss is the most common sensory deficit in Western societies, there are no successful pharmacological treatments for this disorder. Recent experiments have demonstrated that manipulation of intracellular cyclic guanosine monophosphate (cGMP) concentrations can have both beneficial and harmful effects on hearing. In this review, we will examine the role of cGMP as a key second messenger involved in many aspects of cochlear function and discuss the known functions of downstream effectors of cGMP in sound processing. The nitric oxide-stimulated soluble guanylyl cyclase system (sGC) and the two natriuretic peptide-stimulated particulate GCs (pGCs) will be more extensively covered because they have been studied most thoroughly. The cochlear GC systems are attractive targets for medical interventions that improve hearing while simultaneously representing an under investigated source of sensorineural hearing loss.
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Affiliation(s)
- Janet L Fitzakerley
- Department of Biomedical Sciences, University of Minnesota Medical School , Duluth, Minnesota
| | - George J Trachte
- Department of Biomedical Sciences, University of Minnesota Medical School , Duluth, Minnesota
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Ulker P, Özen N, Abdullayeva G, Köksoy S, Yaraş N, Basrali F. Extracellular ATP activates eNOS and increases intracellular NO generation in Red Blood Cells. Clin Hemorheol Microcirc 2018; 68:89-101. [PMID: 29036803 DOI: 10.3233/ch-170326] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND It has been well documented that ATP activates NOS enzymes and causes increased NO production in several cell types. Although RBC known to possesses eNOS enzyme activity, it has not been investigated whether RBC eNOS could be induced by extracellular ATP. OBJECTIVE The aim of the present study is to evaluate extracellular ATP mediated eNOS activation and NO production in RBC. METHODS RBC packed were isolated from healthy volunteers and re-suspended in Hepes solution at a hematocrit of 0.01 l/l. Intracellular NO and Ca+2 levels and eNOS activation measured by flow cytometry in response to P2X receptor agonist, Bz-ATP, in the absence and presence of NOS, P2 receptors and PI3K inhibitors. RESULTS P2X receptor agonist Bz-ATP found to increase intracellular NO, Ca+2 and serine 1177 phosphorylated eNOS levels and these responses have shown to be suppressed by NOS enzyme, P2 receptors and PI3K inhibitors. CONCLUSIONS The results of the study clearly demonstrated extracellular ATP induced NO generation in RBC through intracellular Ca+2 and PI3K/Akt pathways. The mechanism we described here might be important at basal conditions and also in conditions with increased ATP release.
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Affiliation(s)
- Pinar Ulker
- Department of Physiology, Medical Faculty, Akdeniz University, Antalya, Turkey
| | - Nur Özen
- Department of Physiology, Medical Faculty, Akdeniz University, Antalya, Turkey
| | - Günel Abdullayeva
- Department of Physiology, Medical Faculty, Akdeniz University, Antalya, Turkey
| | - Sadi Köksoy
- Department of Medical Microbiology, Medical Faculty, AkdenizUniversity, Antalya, Turkey
| | - Nazmi Yaraş
- Department of Biophysics, Medical Faculty, AkdenizUniversity, Antalya, Turkey
| | - Filiz Basrali
- Department of Physiology, Medical Faculty, Akdeniz University, Antalya, Turkey
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10
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Möhrle D, Reimann K, Wolter S, Wolters M, Varakina K, Mergia E, Eichert N, Geisler HS, Sandner P, Ruth P, Friebe A, Feil R, Zimmermann U, Koesling D, Knipper M, Rüttiger L. NO-Sensitive Guanylate Cyclase Isoforms NO-GC1 and NO-GC2 Contribute to Noise-Induced Inner Hair Cell Synaptopathy. Mol Pharmacol 2017; 92:375-388. [DOI: 10.1124/mol.117.108548] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 07/18/2017] [Indexed: 12/21/2022] Open
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Katz E, Elgoyhen AB. Short-term plasticity and modulation of synaptic transmission at mammalian inhibitory cholinergic olivocochlear synapses. Front Syst Neurosci 2014; 8:224. [PMID: 25520631 PMCID: PMC4251319 DOI: 10.3389/fnsys.2014.00224] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 11/06/2014] [Indexed: 12/23/2022] Open
Abstract
The organ of Corti, the mammalian sensory epithelium of the inner ear, has two types of mechanoreceptor cells, inner hair cells (IHCs) and outer hair cells (OHCs). In this sensory epithelium, vibrations produced by sound waves are transformed into electrical signals. When depolarized by incoming sounds, IHCs release glutamate and activate auditory nerve fibers innervating them and OHCs, by virtue of their electromotile property, increase the amplification and fine tuning of sound signals. The medial olivocochlear (MOC) system, an efferent feedback system, inhibits OHC activity and thereby reduces the sensitivity and sharp tuning of cochlear afferent fibers. During neonatal development, IHCs fire Ca2+ action potentials which evoke glutamate release promoting activity in the immature auditory system in the absence of sensory stimuli. During this period, MOC fibers also innervate IHCs and are thought to modulate their firing rate. Both the MOC-OHC and the MOC-IHC synapses are cholinergic, fast and inhibitory and mediated by the α9α10 nicotinic cholinergic receptor (nAChR) coupled to the activation of calcium-activated potassium channels that hyperpolarize the hair cells. In this review we discuss the biophysical, functional and molecular data which demonstrate that at the synapses between MOC efferent fibers and cochlear hair cells, modulation of transmitter release as well as short term synaptic plasticity mechanisms, operating both at the presynaptic terminal and at the postsynaptic hair-cell, determine the efficacy of these synapses and shape the hair cell response pattern.
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Affiliation(s)
- Eleonora Katz
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Buenos Aires, Argentina ; Departamento de Fisiología, Biología Molecular y Celular "Prof. Héctor Maldonado", Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires Buenos Aires, Argentina
| | - Ana Belén Elgoyhen
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Buenos Aires, Argentina ; Tercera Cátedra de Farmacología, Facultad de Medicina, Universidad de Buenos Aires Buenos Aires, Argentina
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12
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Fuchs PA. A 'calcium capacitor' shapes cholinergic inhibition of cochlear hair cells. J Physiol 2014; 592:3393-401. [PMID: 24566542 PMCID: PMC4229337 DOI: 10.1113/jphysiol.2013.267914] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 02/18/2014] [Indexed: 01/07/2023] Open
Abstract
Efferent cholinergic neurons project from the brainstem to inhibit sensory hair cells of the vertebrate inner ear. This inhibitory synapse combines the activity of an unusual class of ionotropic cholinergic receptor with that of nearby calcium-dependent potassium channels to shunt and hyperpolarize the hair cell. Postsynaptic calcium signalling is constrained by a thin near-membrane cistern that is co-extensive with the efferent terminal contacts. The postsynaptic cistern may play an essential role in calcium homeostasis, serving as sink or source, depending on ongoing activity and the degree of buffer saturation. Release of calcium from postsynaptic stores leads to a process of retrograde facilitation via the synthesis of nitric oxide in the hair cell. Activity-dependent synaptic modification may contribute to changes in hair cell innervation that occur during development, and in the aged or damaged cochlea.
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Affiliation(s)
- Paul Albert Fuchs
- Center for Hearing and Balance, Otolaryngology-Head and Neck Surgery, and Center for Sensory Biology, Institute for Basic Biomedical Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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13
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Kong JH, Zachary S, Rohmann KN, Fuchs PA. Retrograde facilitation of efferent synapses on cochlear hair cells. J Assoc Res Otolaryngol 2012. [PMID: 23183877 DOI: 10.1007/s10162-012-0361-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Cochlear inner hair cells (IHCs) are temporarily innervated by efferent cholinergic fibers prior to the onset of hearing. During low-frequency firing, these efferent synapses have a relatively low probability of transmitter release but facilitate strongly with repetitive stimulation. A retrograde signal from the hair cell to the efferent terminal contributes to this facilitation. When IHCs were treated with the ryanodine receptor agonist, cyclic adenosine phosphoribose (cADPR), release probability of the efferent terminal rose. This effect was quantified by computing the quantum content from a train of 100 suprathreshold stimuli to the efferent fibers. Quantum content was sevenfold higher when IHCs were treated with 100 μM cADPR (applied in the recording pipette). Since cADPR is membrane impermeant, this result implies that an extracellular messenger travels from the hair cell to the efferent terminal. cADPR is presumed to generate this messenger by increasing cytoplasmic calcium. Consistent with this presumption, voltage-gated calcium flux into the IHC also caused retrograde facilitation of efferent transmission. Retrograde facilitation was observed in IHCs of a vesicular glutamate transporter (VGlut3) null mouse and for wild-type rat hair cells subject to wide-spectrum glutamate receptor blockade, demonstrating that glutamate was unlikely to be the extracellular messenger. Rather, bath application of nitric oxide (NO) donors caused an increase in potassium-evoked efferent transmitter release while the NO scavenger carboxy-PTIO was able to prevent retrograde facilitation produced by cADPR or IHC depolarization. Thus, hair cell activity can drive retrograde facilitation of efferent input via calcium-dependent production of NO.
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MESH Headings
- Acoustic Stimulation
- Amino Acid Transport Systems, Acidic/deficiency
- Amino Acid Transport Systems, Acidic/genetics
- Amino Acid Transport Systems, Acidic/metabolism
- Animals
- Calcium/metabolism
- Calcium Channel Agonists/pharmacology
- Dose-Response Relationship, Drug
- Hair Cells, Auditory, Inner/drug effects
- Hair Cells, Auditory, Inner/physiology
- Mice
- Mice, Knockout
- Models, Animal
- Neurons, Efferent/drug effects
- Neurons, Efferent/physiology
- Nitric Oxide/metabolism
- Nitric Oxide Donors/pharmacology
- Rats
- Rats, Inbred Strains
- Synapses/drug effects
- Synapses/physiology
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
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Affiliation(s)
- Jee-Hyun Kong
- Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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14
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cGMP-Prkg1 signaling and Pde5 inhibition shelter cochlear hair cells and hearing function. Nat Med 2012; 18:252-9. [PMID: 22270721 DOI: 10.1038/nm.2634] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 12/07/2011] [Indexed: 02/07/2023]
Abstract
Noise-induced hearing loss (NIHL) is a global health hazard with considerable pathophysiological and social consequences that has no effective treatment. In the heart, lung and other organs, cyclic guanosine monophosphate (cGMP) facilitates protective processes in response to traumatic events. We therefore analyzed NIHL in mice with a genetic deletion of the gene encoding cGMP-dependent protein kinase type I (Prkg1) and found a greater vulnerability to and markedly less recovery from NIHL in these mice as compared to mice without the deletion. Prkg1 was expressed in the sensory cells and neurons of the inner ear of wild-type mice, and its expression partly overlapped with the expression profile of cGMP-hydrolyzing phosphodiesterase 5 (Pde5). Treatment of rats and wild-type mice with the Pde5 inhibitor vardenafil almost completely prevented NIHL and caused a Prkg1-dependent upregulation of poly (ADP-ribose) in hair cells and the spiral ganglion, suggesting an endogenous protective cGMP-Prkg1 signaling pathway that culminates in the activation of poly (ADP-ribose) polymerase. These data suggest vardenafil or related drugs as possible candidates for the treatment of NIHL.
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15
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Harada N. Role of nitric oxide on purinergic signalling in the cochlea. Purinergic Signal 2010; 6:211-20. [PMID: 20806013 DOI: 10.1007/s11302-010-9186-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 05/17/2010] [Indexed: 11/30/2022] Open
Abstract
In the inner ear, there is considerable evidence that extracellular adenosine 5'-triphosphate (ATP) plays an important role in auditory neurotransmission as a neurotransmitter or a neuromodulator, although the potential role of adenosine signalling in the modulation of auditory neurotransmission has also been reported. The activation of ligand-gated ionotropic P2X receptors and G protein-coupled metabotropic P2Y receptors has been reported to induce an increase of intracellular Ca(2+) concentration ([Ca(2+)](i)) in inner hair cells (IHCs), outer hair cells (OHCs), spiral ganglion neurons (SGNs), and supporting cells in the cochlea. ATP may participate in auditory neurotransmission by modulating [Ca(2+)](i) in the cochlear cells. Recent studies showed that extracellular ATP induced nitric oxide (NO) production in IHCs, OHCs, and SGNs, which affects the ATP-induced Ca(2+) response via the NO-cGMP-PKG pathway in those cells by a feedback mechanism. A cross-talk between NO and ATP may therefore exist in the auditory signal transduction. In the present article, I review the role of NO on the ATP-induced Ca(2+) signalling in IHCs and OHCs. I also consider the possible role of NO in the ATP-induced Ca(2+) signalling in SGNs and supporting cells.
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Affiliation(s)
- Narinobu Harada
- Harada Ear Institute, Tomoi 2-34-27, Higashiosaka, Osaka, 577-0816 Japan
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16
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Neuroprotective effects of (-)-epigallocatechin-3-gallate against quinolinic acid-induced excitotoxicity via PI3K pathway and NO inhibition. Brain Res 2009; 1313:25-33. [PMID: 20025854 DOI: 10.1016/j.brainres.2009.12.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 11/26/2009] [Accepted: 12/07/2009] [Indexed: 12/17/2022]
Abstract
Excessive stimulation of the NMDA receptor induces neuronal cell death and is implicated in the development of several neurodegenerative diseases. While EGCG suppresses apoptosis induced by NMDA receptor-mediated excitotoxicity, the mechanisms underlying this process have yet to be completely determined. This study was designed to investigate whether (-)-epigallocatechin-3-gallate (EGCG) plays a neuroprotective role by inhibiting nitric oxide (NO) production and activating cellular signaling mechanisms including MAP kinase, PI3K, and GSK-3beta and acting on the antiapoptotic and the proapoptotic genes in N18D3 neural cells. The cells were pretreated with EGCG for 2 h and then exposed to quinolinic acid (QUIN), a NMDA receptor agonist, 30 mM for 24 h. MTT assay and DAPI staining were used to identify cell viability and apoptosis, respectively, and demonstrated that EGCG significantly increased cell viability and protected the cells from apoptotic death. In addition, EGCG had a capacity to reduce QUIN-induced excitotoxic cell death not only by blocking increase of intracellular calcium levels but also by inhibiting NO production. Gene expression analysis revealed that EGCG prevented the QUIN-induced expression of the proapoptotic gene, caspase-9, and increased that of the antiapoptotic genes, Bcl-XL, Bcl-2, and Bcl-w. Further examination about potential cell signaling candidate involved in this neuroprotective effect showed that immunoreacitivity of PI3K was significantly increased in the cells treated with EGCG. These results suggest that the neuroprotective mechanism of EGCG against QUIN-induced excitotoxic cell death includes regulation of PI3K and modulation of cell survival and death genes through decreasing of intracellular calcium levels and controlling of NO production.
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17
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Abstract
P2X and P2Y nucleotide receptors are described on sensory neurons and their peripheral and central terminals in dorsal root, nodose, trigeminal, petrosal, retinal and enteric ganglia. Peripheral terminals are activated by ATP released from local cells by mechanical deformation, hypoxia or various local agents in the carotid body, lung, gut, bladder, inner ear, eye, nasal organ, taste buds, skin, muscle and joints mediating reflex responses and nociception. Purinergic receptors on fibres in the dorsal spinal cord and brain stem are involved in reflex control of visceral and cardiovascular activity, as well as relaying nociceptive impulses to pain centres. Purinergic mechanisms are enhanced in inflammatory conditions and may be involved in migraine, pain, diseases of the special senses, bladder and gut, and the possibility that they are also implicated in arthritis, respiratory disorders and some central nervous system disorders is discussed. Finally, the development and evolution of purinergic sensory mechanisms are considered.
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18
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Foresi NP, Laxalt AM, Tonón CV, Casalongué CA, Lamattina L. Extracellular ATP induces nitric oxide production in tomato cell suspensions. PLANT PHYSIOLOGY 2007; 145:589-92. [PMID: 17984199 PMCID: PMC2048788 DOI: 10.1104/pp.107.106518] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 09/07/2007] [Indexed: 05/20/2023]
Affiliation(s)
- Noelia P Foresi
- Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina
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19
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Florenzano F, Viscomi MT, Amadio S, D'Ambrosi N, Volonté C, Molinari M. Do ATP and NO interact in the CNS? Prog Neurobiol 2007; 84:40-56. [PMID: 18036717 DOI: 10.1016/j.pneurobio.2007.10.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 08/01/2007] [Accepted: 10/05/2007] [Indexed: 02/08/2023]
Abstract
Enzymatically derived NO and extracellular ATP are receiving greater attention due to their role as messengers in the CNS during different physiological and pathological processes. Ionotropic (P2XR) and metabotropic (P2YR) purinergic receptors mediate ATP effects and are present throughout the body. Particularly P2XR are crucial for brain plasticity mechanisms, and are involved in the pathogenesis of different CNS illnesses. NO does not have a specific receptor and its actions are directly dependent on the production on demand by different nitric oxide synthase isoforms. NO synthesizing enzymes are present virtually in all tissues, and NO influences multifarious physiological and pathological functions. Interestingly, various are the tissue and organs modulated by both ATP and NO, such as the immune, brain and vascular systems. Moreover, direct interactions between purinergic and nitrergic mechanisms outside the CNS are well documented, with several studies also indicating that ATP and NO do participate to the same CNS functions. In the past few years, further experimental evidence supported the physiological and pathological relevance of ATP and NO direct interactions in the CNS. The aim of the present review is to provide an account of the available information on the interplay between purinergic and nitrergic systems, focussing on the CNS. The already established relevance of ATP and NO in different pathological processes would predict that the knowledge of ATP/NO cross-talk mechanisms would support pharmacological approaches toward the development of novel ATP/NO combined pharmacological agents.
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Affiliation(s)
- F Florenzano
- Experimental Neurorehabilitation Laboratory, I.R.C.C.S. Santa Lucia Foundation, Via del Fosso di Fiorano 65, 00143 Rome, Italy
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20
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Takeda-Nakazawa H, Harada N, Shen J, Kubo N, Zenner HP, Yamashita T. Hyposmotic stimulation-induced nitric oxide production in outer hair cells of the guinea pig cochlea. Hear Res 2007; 230:93-104. [PMID: 17722255 DOI: 10.1016/j.heares.2007.05.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Nitric oxide (NO) production during hyposmotic stimulation in outer hair cells (OHCs) of the guinea pig cochlea was investigated using the NO sensitive dye DAF-2. Simultaneous measurement of the cell length and NO production showed rapid hyposmotic-induced cell swelling to precede NO production in OHCs. Hyposmotic stimulation failed to induce NO production in the Ca2+-free solution. L-NG-nitroarginine methyl ester (L-NAME), a non-specific NO synthase inhibitor and gadolinium, a stretch-activated channel blocker inhibited the hyposmotic stimulation-induced NO production whereas suramin, a P2 receptor antagonist did not. S-nitroso-N-acetylpenicillamine (SNAP), a NO donor inhibited the hyposmotic stimulation-induced increase in the intracellular Ca2+ concentrations ([Ca2+]i) while L-NAME enhanced it. 1H-[1,2,4]oxadiazole[4,3a]quinoxalin-1-one, an inhibitor of guanylate cyclase and KT5823, an inhibitor of cGMP-dependent protein kinase (PKG) mimicked effects of L-NAME on the Ca2+ response. Transient receptor potential vanilloid 4 (TRPV4), an osmo- and mechanosensitive channel was expressed in the OHCs by means of immunohistochemistry. 4alpha-phorbol 12,13-didecanoate, a TRPV4 synthetic activator, induced NO production in OHCs. These results suggest that hyposmotic stimulation can induce NO production by the [Ca2+]i increase, which is presumably mediated by the activation of TRPV4 in OHCs. NO conversely inhibits the Ca2+ response via the NO-cGMP-PKG pathway by a feedback mechanism.
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Affiliation(s)
- Hiroko Takeda-Nakazawa
- Hearing Research Laboratory, Department of Otolaryngology, Kansai Medical University, Fumizonocho 10-15, Moriguchi, Osaka 570-8507, Japan
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21
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Abstract
This review is focused on purinergic neurotransmission, i.e., ATP released from nerves as a transmitter or cotransmitter to act as an extracellular signaling molecule on both pre- and postjunctional membranes at neuroeffector junctions and synapses, as well as acting as a trophic factor during development and regeneration. Emphasis is placed on the physiology and pathophysiology of ATP, but extracellular roles of its breakdown product, adenosine, are also considered because of their intimate interactions. The early history of the involvement of ATP in autonomic and skeletal neuromuscular transmission and in activities in the central nervous system and ganglia is reviewed. Brief background information is given about the identification of receptor subtypes for purines and pyrimidines and about ATP storage, release, and ectoenzymatic breakdown. Evidence that ATP is a cotransmitter in most, if not all, peripheral and central neurons is presented, as well as full accounts of neurotransmission and neuromodulation in autonomic and sensory ganglia and in the brain and spinal cord. There is coverage of neuron-glia interactions and of purinergic neuroeffector transmission to nonmuscular cells. To establish the primitive and widespread nature of purinergic neurotransmission, both the ontogeny and phylogeny of purinergic signaling are considered. Finally, the pathophysiology of purinergic neurotransmission in both peripheral and central nervous systems is reviewed, and speculations are made about future developments.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neurscience Centre, Royal Free and University College Medical School, London, UK.
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22
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Takeda-Nakazawa H, Harada N, Shen J, Kubo N, Zenner HP, Yamashita T. Hyposmotic stimulation-induced nitric oxide production in outer hair cells of the guinea pig cochlea. Hear Res 2006; 227:59-70. [PMID: 17092670 DOI: 10.1016/j.heares.2006.09.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 05/06/2006] [Accepted: 09/24/2006] [Indexed: 10/23/2022]
Abstract
Nitric oxide (NO) production during hyposmotic stimulation in outer hair cells (OHCs) of the guinea pig cochlea was investigated using the NO sensitive dye DAF-2. Simultaneous measurement of the cell length and NO production showed rapid hyposmotic-induced cell swelling to precede NO production in OHCs. Hyposmotic stimulation failed to induce NO production in the Ca(2+)-free solution. L-N(G)-nitroarginine methyl ester (L-NAME), a non-specific NO synthase inhibitor and gadolinium, a stretch-activated channel blocker inhibited the hyposmotic stimulation-induced NO production whereas suramin, a P2 receptor antagonist did not. S-nitroso-N-acetylpenicillamine (SNAP), a NO donor inhibited the hyposmotic stimulation-induced increase in the intracellular Ca(2+) concentrations ([Ca(2+)](i)) while L-NAME enhanced it. 1H-[1,2,4]oxadiazole[4,3a]quinoxalin-1-one, an inhibitor of guanylate cyclase and KT5823, an inhibitor of cGMP-dependent protein kinase (PKG) mimicked effects of L-NAME on the Ca(2+) response. Transient receptor potential vanilloid 4 (TRPV4), an osmo- and mechanosensitive channel was expressed in the OHCs by means of immunohistochemistry. 4alpha-phorbol 12,13-didecanoate, a TRPV4 synthetic activator, induced NO production in OHCs. These results suggest that hyposmotic stimulation can induce NO production by the [Ca(2+)](i) increase, which is presumably mediated by the activation of TRPV4 in OHCs. NO conversely inhibits the Ca(2+) response via the NO-cGMP-PKG pathway by a feedback mechanism.
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Affiliation(s)
- Hiroko Takeda-Nakazawa
- Hearing Research Laboratory, Department of Otolaryngology, Kansai Medical University, Fumizonocho 10-15, Moriguchi, Osaka 570-8507, Japan
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