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Kawai F. Somatic ion channels and action potentials in olfactory receptor cells and vomeronasal receptor cells. J Neurophysiol 2024; 131:455-471. [PMID: 38264787 DOI: 10.1152/jn.00137.2023] [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: 04/02/2023] [Revised: 01/10/2024] [Accepted: 01/17/2024] [Indexed: 01/25/2024] Open
Abstract
Olfactory receptor cells are primary sensory neurons that catch odor molecules in the olfactory system, and vomeronasal receptor cells catch pheromones in the vomeronasal system. When odor or pheromone molecules bind to receptor proteins expressed on the membrane of the olfactory cilia or vomeronasal microvilli, receptor potentials are generated in their receptor cells. This initial excitation is transmitted to the soma via dendrites, and action potentials are generated in the soma and/or axon and transmitted to the central nervous system. Thus, olfactory and vomeronasal receptor cells play an important role in converting chemical signals into electrical signals. In this review, the electrophysiological characteristics of ion channels in the somatic membrane of olfactory receptor cells and vomeronasal receptor cells in various species are described and the differences between the action potential dynamics of olfactory receptor cells and vomeronasal receptor cells are compared.
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Affiliation(s)
- Fusao Kawai
- Department of Physiology, School of Medicine, Fujita Health University, Toyoake, Aichi, Japan
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2
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Hernandez-Clavijo A, Sánchez Triviño CA, Guarneri G, Ricci C, Mantilla-Esparza FA, Gonzalez-Velandia KY, Boscolo-Rizzo P, Tofanelli M, Bonini P, Dibattista M, Tirelli G, Menini A. Shedding light on human olfaction: Electrophysiological recordings from sensory neurons in acute slices of olfactory epithelium. iScience 2023; 26:107186. [PMID: 37456832 PMCID: PMC10345129 DOI: 10.1016/j.isci.2023.107186] [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: 04/13/2023] [Revised: 05/19/2023] [Accepted: 06/16/2023] [Indexed: 07/18/2023] Open
Abstract
The COVID-19 pandemic brought attention to our limited understanding of human olfactory physiology. While the cellular composition of the human olfactory epithelium is similar to that of other vertebrates, its functional properties are largely unknown. We prepared acute slices of human olfactory epithelium from nasal biopsies and used the whole-cell patch-clamp technique to record electrical properties of cells. We measured voltage-gated currents in human olfactory sensory neurons and supporting cells, and action potentials in neurons. Additionally, neuronal inward current and action potentials responses to a phosphodiesterase inhibitor suggested a transduction cascade involving cAMP as a second messenger. Furthermore, responses to odorant mixtures demonstrated that the transduction cascade was intact in this preparation. This study provides the first electrophysiological characterization of olfactory sensory neurons in acute slices of the human olfactory epithelium, paving the way for future research to expand our knowledge of human olfactory physiology.
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Affiliation(s)
- Andres Hernandez-Clavijo
- Neuroscience Area, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | | | - Giorgia Guarneri
- Neuroscience Area, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | - Chiara Ricci
- Neuroscience Area, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | | | | | - Paolo Boscolo-Rizzo
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy
| | - Margherita Tofanelli
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy
| | - Pierluigi Bonini
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy
| | - Michele Dibattista
- Department of Translational Biomedicine and Neuroscience, University of Bari A. Moro, 70121 Bari, Italy
| | - Giancarlo Tirelli
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy
| | - Anna Menini
- Neuroscience Area, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
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3
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Orfali R, AlFaiz A, Rahman MA, Lau L, Nam YW, Zhang M. K Ca2 and K Ca3.1 Channels in the Airways: A New Therapeutic Target. Biomedicines 2023; 11:1780. [PMID: 37509419 PMCID: PMC10376499 DOI: 10.3390/biomedicines11071780] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/08/2023] [Accepted: 06/13/2023] [Indexed: 07/30/2023] Open
Abstract
K+ channels are involved in many critical functions in lung physiology. Recently, the family of Ca2+-activated K+ channels (KCa) has received more attention, and a massive amount of effort has been devoted to developing selective medications targeting these channels. Within the family of KCa channels, three small-conductance Ca2+-activated K+ (KCa2) channel subtypes, together with the intermediate-conductance KCa3.1 channel, are voltage-independent K+ channels, and they mediate Ca2+-induced membrane hyperpolarization. Many KCa2 channel members are involved in crucial roles in physiological and pathological systems throughout the body. In this article, different subtypes of KCa2 and KCa3.1 channels and their functions in respiratory diseases are discussed. Additionally, the pharmacology of the KCa2 and KCa3.1 channels and the link between these channels and respiratory ciliary regulations will be explained in more detail. In the future, specific modulators for small or intermediate Ca2+-activated K+ channels may offer a unique therapeutic opportunity to treat muco-obstructive lung diseases.
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Affiliation(s)
- Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
- Biomedical Research Administration, Research Centre, King Fahad Medical City, Riyadh Second Health Cluster, Riyadh 12231, Saudi Arabia
| | - Ali AlFaiz
- Biomedical Research Administration, Research Centre, King Fahad Medical City, Riyadh Second Health Cluster, Riyadh 12231, Saudi Arabia
| | - Mohammad Asikur Rahman
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Liz Lau
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
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Ozdener MH, Rockx B, Rawson NE. Primary Culture of the Human Olfactory Neuroepithelium and Utilization for Henipavirus Infection In Vitro. Methods Mol Biol 2023; 2682:121-133. [PMID: 37610578 DOI: 10.1007/978-1-0716-3283-3_9] [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] [Indexed: 08/24/2023]
Abstract
The olfactory receptor neurons (ORNs) are a unique cell type involved in the initial perception of odors. These specialized epithelial cells are located in the neuroepithelium of the nasal cavities and directly connect the nasal cavity with the central nervous system (CNS) via axons, which traverse the cribriform plate to synapse within the olfactory bulb. ORNs are derived from precursor cells that lie adjacent to the basal lamina of the olfactory epithelium. These precursor cells divide several times and their progeny differentiate into mature sensory neurons throughout life. In addition to its major and critical role in sensory transduction, the olfactory neuroepithelium may be an important tissue for viral replication and represents a potential site for viral entry into the CNS. In general, to gain access to the CNS, neurotropic viruses such as henipaviruses can use peripheral neural pathways or the circulatory system. However, the olfactory system has been reported to provide a portal of entry to the CNS for henipaviruses. The ability to obtain biopsies from living human subjects and culture these cells in the laboratory provides the opportunity to examine viral replication and effects on a neuronal cell population. As the most exposed and unprotected segment of the nervous system, the olfactory neuroepithelium may have an important role in neuropathology and systemic dissemination of viruses with established CNS effects. This chapter presents methods for primary culture of human ORNs, which have been used successfully by multiple investigators. The protocol provides a consistent, heterogeneous olfactory epithelial cell population, which demonstrates functional responses to odorant mixtures and exhibits several key features of the olfactory receptor neuron phenotype, encompassing olfactory receptors and signaling pathways.
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Affiliation(s)
| | - Barry Rockx
- Wageningen Bioveterinary Institute, Lelystad and Department of Viroscience, Erasmus University Medical Center, Rotterdam, The Netherlands
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Kim K, Zhao K. A Nasal Aerodynamics Perspective of Retronasal Olfaction: Rodents vs. Humans. CHEMOSENS PERCEPT 2022; 15:124-134. [PMID: 37192933 PMCID: PMC10168102 DOI: 10.1007/s12078-022-09300-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 09/28/2022] [Indexed: 11/03/2022]
Abstract
Introduction Odor perception can be achieved through ortho or retronasal routes, with the latter being an important component of flavor perception. There are significant olfactory differences that exist between rats and humans and by understanding the role of structural differences, further insight can be gained into the mechanism of odorant perception via ortho or retronasal routes. Methods 3D human and rat (Sprague Dawley) computational models were used to investigate nasal anatomy impact on ortho vs. retronasal odorant transport to the olfactory epithelium. The nasal pharynx region was modified for human and rat models to probe nasal structure impact on ortho vs retro olfaction. 65 odorant absorption rates to the olfactory epithelium were extracted from each model. Results For human, the retronasal route provided higher peak odorant absorption compared to orthonasal route (left: 90% higher, right: 45% higher), but substantially lowered peak absorption for rat (medial: 97% lower, lateral: 75% lower). For both models, anatomical modification had minimal impact to orthonasal routes, but substantially modulated the retronasal route: decrease (left: -41.4%, right: -44.2%) for human, and increase to the medial (29.5%) but not to lateral (-14.3%) for rat. Conclusions There exist key differences between humans and rats regarding retro/orthonasal odorant transport routes, which matched well with experimental olfactory bulb activity data in literature. Implications While humans have equivalent odorant delivery between routes, the difference in retro and orthonasal routes in rodents is substantial and changes to the transverse lamina above the nasopharynx can substantially modulate the retronasal route, but not enough to bridge the gap between the two routes.
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Affiliation(s)
- Kanghyun Kim
- Department of Otolaryngology - Head & Neck Surgery, The Ohio State University, Columbus, OH
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH
| | - Kai Zhao
- Department of Otolaryngology - Head & Neck Surgery, The Ohio State University, Columbus, OH
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH
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Kurihara S, Tei M, Hata J, Mori E, Fujioka M, Matsuwaki Y, Otori N, Kojima H, Okano HJ. MRI tractography reveals the human olfactory nerve map connecting the olfactory epithelium and olfactory bulb. Commun Biol 2022; 5:843. [PMID: 36068329 PMCID: PMC9448749 DOI: 10.1038/s42003-022-03794-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 08/03/2022] [Indexed: 11/16/2022] Open
Abstract
The olfactory nerve map describes the topographical neural connections between the olfactory epithelium in the nasal cavity and the olfactory bulb. Previous studies have constructed the olfactory nerve maps of rodents using histological analyses or transgenic animal models to investigate olfactory nerve pathways. However, the human olfactory nerve map remains unknown. Here, we demonstrate that high-field magnetic resonance imaging and diffusion tensor tractography can be used to visualize olfactory sensory neurons while maintaining their three-dimensional structures. This technique allowed us to evaluate the olfactory sensory neuron projections from the nasal cavities to the olfactory bulbs and visualize the olfactory nerve maps of humans, marmosets and mice. The olfactory nerve maps revealed that the dorsal-ventral and medial-lateral axes were preserved between the olfactory epithelium and olfactory bulb in all three species. Further development of this technique might allow it to be used clinically to facilitate the diagnosis of olfactory dysfunction. Combined high-field MRI and DTI analyses in post-mortem mouse, marmoset, and human samples provide insight into the neural connections between nasal cavities and olfactory bulbs.
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Affiliation(s)
- Sho Kurihara
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan.
| | - Masayoshi Tei
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan
| | - Junichi Hata
- Division of Regenerative Medicine, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan.,Graduate School of Human Health Sciences, Tokyo Metropolitan University, 7-2-10 Higashi-Ogu Arakawa-ku, Tokyo, 116-8551, Japan
| | - Eri Mori
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan
| | - Masato Fujioka
- Department of Molecular Genetics, Kitasato University School of Medicine, 1-15-1 Kitasato Minami-ku Sagamihara-shi, Kanagawa, 252-0373, Japan.,Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, 35 Shinanomachi Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Yoshinori Matsuwaki
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan
| | - Nobuyoshi Otori
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan
| | - Hiromi Kojima
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan
| | - Hirotaka James Okano
- Division of Regenerative Medicine, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan.
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Chen M, Liu J, Luo H, Duan C, Gao G, Yang H. Increase in membrane surface expression and phosphorylation of TRPC3 related to olfactory dysfunction in α-synuclein transgenic mice. J Cell Mol Med 2022; 26:5008-5020. [PMID: 36029194 PMCID: PMC9549507 DOI: 10.1111/jcmm.17524] [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: 12/24/2021] [Revised: 08/05/2022] [Accepted: 08/10/2022] [Indexed: 11/28/2022] Open
Abstract
Olfactory impairment is an initial non-motor symptom of Parkinson's disease that causes the deposition of aggregated α-synuclein (α-syn) in olfactory neurons. Transient receptor potential canonical (TRPC) channels are a diverse group of non-selective Ca2+ entry channels involved in the progression or pathogenesis of PD via Ca2+ homeostatic regulation. However, the relationship between TRPC and α-syn pathology in an olfactory system remains unclear. To address this issue, we assessed the olfactory function in α-syn transgenic mice. In contrast with control mice, the transgenic mice exhibited impaired olfaction, TRPC3 activation and apoptotic neuronal cell death in the olfactory system. Similar results were observed in primary cultures of olfactory neurons, that is TRPC3 activation, increasing intracellular Ca2+ concentration and apoptotic cell death in the α-syn-overexpressed neurons. These changes were significantly attenuated by TRPC3 knockdown. Therefore, our findings suggest that TRPC3 activation and calcium dyshomeostasis play a key role in α-syn-induced olfactory dysfunction in mice.
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Affiliation(s)
- Min Chen
- Department of Neurobiology School of Basic Medical Sciences, Key Laboratory of Neural Regeneration and Repair, Center for Parkinson's Disease, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Guangxi Neurological Disease Clinical Research Center, Laboratory of Neuroscience, Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Jia Liu
- Department of Neurobiology School of Basic Medical Sciences, Key Laboratory of Neural Regeneration and Repair, Center for Parkinson's Disease, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Hanjiang Luo
- Guangxi Neurological Disease Clinical Research Center, Laboratory of Neuroscience, Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Chunli Duan
- Department of Neurobiology School of Basic Medical Sciences, Key Laboratory of Neural Regeneration and Repair, Center for Parkinson's Disease, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Ge Gao
- Department of Neurobiology School of Basic Medical Sciences, Key Laboratory of Neural Regeneration and Repair, Center for Parkinson's Disease, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Hui Yang
- Department of Neurobiology School of Basic Medical Sciences, Key Laboratory of Neural Regeneration and Repair, Center for Parkinson's Disease, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
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Griffiths CF, Barkhoudarian G, Cutler A, Duong HT, Karimi K, Doyle O, Carrau R, Kelly DF. Analysis of Olfaction after Bilateral Nasoseptal Rescue Flap Transsphenoidal Approach with Olfactory Mucosal Preservation. Otolaryngol Head Neck Surg 2019; 161:881-889. [PMID: 31331243 DOI: 10.1177/0194599819861340] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To ascertain the impact of septal olfactory strip preservation and bilateral rescue flap elevation on the incidence of olfactory dysfunction. STUDY DESIGN Case series with chart review of patients undergoing endoscopic endonasal skull base surgery (2012-2014). SETTING Providence Saint John's Health Center and John Wayne Cancer Institute. SUBJECTS AND METHODS The incidences of postoperative epistaxis, hyposmia, and anosmia were analyzed using the Brief Smell Identification Test (B-SIT), which was completed in 110 of the 165 patients. RESULTS Seventy-eight patients required extended approaches. Bilateral nasoseptal rescue flaps were elevated in 144 patients (87.3%) and pedicled nasoseptal or middle turbinate flaps in 21 patients (12.7%). The neurovascular pedicles were preserved in all patients, and there were no episodes of postoperative arterial epistaxis. Normal olfaction was noted in 95 patients (86%), with new hyposmia noted in 5 patients (5.5%). Within the rescue flap cohort, new hyposmia occurred in 6.3% (P < .01) of patients, balanced by improvement of olfaction in 43% of patients with preoperative dysfunction (overall pre- and postoperative olfactory function: 85% vs 86%). Patients with pedicled nasoseptal flaps did not have new hyposmia, with a net improvement of olfaction (71% vs 86%, P = .07). No patients experienced new anosmia. There was no difference between flap type within either subgroup. CONCLUSIONS Superior olfactory strip preservation during elevation of reconstructive flaps preserves olfactory function and maintains adequate surgical exposure. In addition, rescue flaps have significantly diminished the rate of arterial postoperative epistaxis while maintaining the ability to harvest nasoseptal flaps for future reconstruction.
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Affiliation(s)
- Chester F Griffiths
- Pacific Neuroscience Institute & Pituitary Disorders Program, John Wayne Cancer Institute at Providence Saint John's Health Center, Santa Monica, California, USA
| | - Garni Barkhoudarian
- Pacific Neuroscience Institute & Pituitary Disorders Program, John Wayne Cancer Institute at Providence Saint John's Health Center, Santa Monica, California, USA
| | - Aaron Cutler
- Inland Neurosurgery Institute, Pomona, California, USA
| | - Huy T Duong
- University of California, Davis Medical School, Davis, California and The Kaiser Permanente Medical Group, Sacramento, California, USA
| | - Kian Karimi
- Pacific Eye and Ear Specialists, Los Angeles, California, USA
| | - Olivia Doyle
- Pacific Eye and Ear Specialists, Los Angeles, California, USA
| | - Ricardo Carrau
- Comprehensive Skull Base Surgery Program, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Daniel F Kelly
- Pacific Neuroscience Institute & Pituitary Disorders Program, John Wayne Cancer Institute at Providence Saint John's Health Center, Santa Monica, California, USA
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Tamari K, Takeuchi H, Kobayashi M, Takeuchi K, Kurahashi T, Yamamoto T. Electrical properties of cells from human olfactory epithelium. Auris Nasus Larynx 2019; 46:734-741. [PMID: 30850172 DOI: 10.1016/j.anl.2019.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 12/19/2018] [Accepted: 01/14/2019] [Indexed: 11/30/2022]
Abstract
OBJECTIVE The electrical properties of olfactory cells (OCs) are typically examined using animals such as newts, mice, and frogs, with few studies on human OCs. This study investigated the electrical properties of human cells from olfactory epithelium (hCOEs) obtained from subjects of olfactory epithelium showing no clinical symptoms during endoscopic sinus surgery. METHODS hCOEs were isolated by collagenase treatment for whole-cell patch clamp recording. The identity of the cells was confirmed by immunohistochemistry with an antibody against olfactory maker protein. Under the voltage clamp with the whole-cell recording configuration, the voltage-gated currents of isolated hCOEs were recorded when the membrane potential was depolarized from a holding potential of -100 mV in a stepwise manner between -90 mV and + 40 mV. RESULTS Only one of 14 hCOE samples expressed a transient inward current at the depolarizing voltage step that was activated by depolarization beyond -40 mV and reached a peak at -30 mV. Delayed and sustained outward currents (444 ± 106 pA at + 40 mV pulse; n = 20) were suppressed by tetraethyl ammonium (n = 3), which is consistent with the properties of newt OCs. CONCLUSIONS Most hCOEs did not exhibit the transient inward current observed in animal models. These findings provide insight into the physiological basis of the unique aspects of human olfactory signal transduction.
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Affiliation(s)
- Kengo Tamari
- College of Liberal Arts and Sciences, Mie University, Tsu, Mie 514-8507, Japan; Department of Otorhinolaryngology-Head and Neck Surgery, Mie University Graduate School of Medicine, Tsu, Mie 514-8507, Japan.
| | - Hiroko Takeuchi
- Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Masayoshi Kobayashi
- Department of Otorhinolaryngology-Head and Neck Surgery, Mie University Graduate School of Medicine, Tsu, Mie 514-8507, Japan
| | - Kazuhiko Takeuchi
- Department of Otorhinolaryngology-Head and Neck Surgery, Mie University Graduate School of Medicine, Tsu, Mie 514-8507, Japan
| | - Takashi Kurahashi
- Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Tetsuro Yamamoto
- Department of Neurophysiology, Mie University Graduate School of Medicine, Tsu, Mie 514-8507, Japan
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O'Neill G, Musto C, Gomez G. Chronic odorant exposure upregulates acquisition of functional properties in cultured embryonic chick olfactory sensory neurons. J Neurosci Res 2016; 95:1216-1224. [PMID: 27714890 DOI: 10.1002/jnr.23966] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/22/2016] [Accepted: 09/23/2016] [Indexed: 01/30/2023]
Abstract
Neuronal development and differentiation is modulated by activity-dependent mechanisms that stimulate endogenous neurogenesis and differentiation to promote adaptive survival of the organism. Studies on bird odor imprinting have shown how sensory stimuli or environmental influences can affect neonatal behavior, presumably by remodeling the developing nervous system. It is unclear whether these changes originate from the sensory neurons themselves or from the brain. Thus, we attempted to address this by using an in vitro system to separate the peripheral neurons from their central connections. Olfactory neurons from embryonic day 17 Gallus domesticus chicks were isolated, cultured, and exposed to 100 µM amyl acetate or phenethyl alcohol in 12-hr bouts, alternated with periods of no-odor exposure. On days 4 and 5 in vitro, cells were immunostained for olfactory marker protein, neuron-specific tubulin, and olfactory GTP-binding protein, and tested for odorant sensitivity using calcium imaging. While odorant exposure did not result in a significant increase in the overall number of neurons, it promoted neuron differentiation: a larger proportion of odorant-exposed cells expressed olfactory marker protein and the olfactory GTP-binding protein. When cell responsiveness was tested using calcium imaging, a greater proportion of odorant-exposed cells responded to stimulation with 100 µM amyl acetate or phenethyl alcohol. Thus, odorant exposure during development modulated the developmental trajectories of individual neurons, resulting in changes in protein expression associated with odorant signaling. This suggests that the neuronal changes in the periphery have an important contribution to the overall long-term functional changes associated with odor imprinting. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Grace O'Neill
- Biology Department, University of Scranton, Scranton, Pennsylvania.,Pennsylvania State College of Medicine, Hershey, Pennsylvania
| | - Christa Musto
- Biology Department, University of Scranton, Scranton, Pennsylvania.,University of Pittsburgh School of Dental Medicine, Pittsburgh, Pennsylvania
| | - George Gomez
- Biology Department, University of Scranton, Scranton, Pennsylvania
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11
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Griffiths CF, Cutler AR, Duong HT, Bardo G, Karimi K, Barkhoudarian G, Carrau R, Kelly DF. Avoidance of postoperative epistaxis and anosmia in endonasal endoscopic skull base surgery: a technical note. Acta Neurochir (Wien) 2014; 156:1393-401. [PMID: 24809531 DOI: 10.1007/s00701-014-2107-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 04/19/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Most endoscopic transsphenoidal approaches jeopardize the sphenopalatine artery and septal olfactory strip (SOS), increasing the risk of postoperative anosmia and epistaxis while precluding the ability to raise pedicled nasoseptal flaps (NSF). We describe a bilateral "rescue flap" technique that preserves the mucosa containing the nasal-septal vascular pedicles and the SOS. This approach can reduce the risk of postoperative complications, including epistaxis and anosmia. METHODS A retrospective analysis was conducted of all patients who underwent endoscopic transsphenoidal surgery with preservation of both sphenopalatine vascular pedicles and SOS. In a recent subset of patients, olfactory assessment was performed. RESULTS Of 174 consecutive operations performed in 161 patients, bilateral preservation of the sphenopalatine vascular pedicle and SOS was achieved in 139 (80 %) operations, including 31 (22 %) with prior transsphenoidal surgery. Of the remaining 35 operations, 18 had a planned formal NSF and 17 had prior surgery or extensive lesions precluding use of this technique. Of pituitary adenomas, RCCs or sellar arachnoid cysts, 118 (94 %) underwent this approach, including 91 % of patients who had prior surgery. Preoperative olfaction function was maintained in 97 % of patients that were tested. None of the patients had postoperative arterial epistaxis. CONCLUSION Preservation of bilateral sphenopalatine vascular pedicles and the SOS is feasible in over 90 % of patients undergoing endonasal endoscopic surgery for pituitary adenomas and RCCs. This approach, while not hindering exposure or limiting instrument maneuverability, preserves the nasoseptal vasculature for future NSF use if needed and appears to minimize the risks of postoperative arterial epistaxis and anosmia.
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Affiliation(s)
- Chester F Griffiths
- Saint Johns Medical Center, John Wayne Cancer Institute, 2200 Santa Monica Blvd, Santa Monica, CA, 90404, USA
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12
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Zhao K, Jiang J, Pribitkin EA, Dalton P, Rosen D, Lyman B, Yee KK, Rawson NE, Cowart BJ. Conductive olfactory losses in chronic rhinosinusitis? A computational fluid dynamics study of 29 patients. Int Forum Allergy Rhinol 2014; 4:298-308. [PMID: 24449655 DOI: 10.1002/alr.21272] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 11/06/2013] [Accepted: 11/26/2013] [Indexed: 11/06/2022]
Abstract
BACKGROUND Besides sensorineural factors, conductive impediments likely contribute to olfactory losses in chronic rhinosinusitis (CRS) patients, yet no conclusive evidence exists. We aimed to examine possible conductive factors using computational fluid dynamics (CFD) models. METHODS A total of 29 CRS patients were assessed via odorant detection thresholds (ODTs), rhinomanometry (nasal resistance [NR]), acoustic rhinometry (minimum-cross-sectional area [MCA]) and computed tomography (CT) staging. CFD simulations of nasal airflow and odorant absorption to olfactory region were carried out based on individual CTs. Biopsies of olfactory epithelium (OE) were collected, cryosectioned, stained, and scored for erosion. RESULTS Significant correlations to ODTs were found for 3 variables: odor absorption in the olfactory region (r = -0.60, p < 0.01), MCA (r = -0.40, p < 0.05), and CT staging (r = 0.42, p < 0.05). However, significant findings were limited to ODTs of the highly soluble l-carvone. Multiple regression analysis revealed that these variables combined, with the addition of NR, can account for 65% of the total variance in ODTs. CT staging correlated significantly with OE erosion (r = 0.77, p < 0.01) and can replace the latter in the regression with comparable outcomes. Partial correlations suggest the contributions of both conductive and sensorineural variables are more prominent if adjusted for the effects of the other. Olfactory loss and inflammatory factors have strong bilateral involvement, whereas conductive factors are independent between sides. As validation, CFD-simulated NRs significantly correlated with rhinomanometrically assessed NRs (r = 0.60, p < 0.01). CONCLUSION Both conductive and sensorineural mechanisms can contribute to olfactory losses in CRS. CFD modeling provides critical guidance in understanding the role of conductive impediments in olfactory dysfunction in CRS.
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Affiliation(s)
- Kai Zhao
- Monell Chemical Senses Center, Philadelphia, PA; Department of Otolaryngology, Thomas Jefferson University, Philadelphia, PA
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13
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Activation of olfactory receptors on mouse pulmonary macrophages promotes monocyte chemotactic protein-1 production. PLoS One 2013; 8:e80148. [PMID: 24278251 PMCID: PMC3836993 DOI: 10.1371/journal.pone.0080148] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 09/29/2013] [Indexed: 12/31/2022] Open
Abstract
Background Emerging evidence suggests that non-olfactory tissues and cells can express olfactory receptors (ORs), however, the exact function of ectopic OR expression remains unknown. We have previously shown in mouse models that a unique cooperation between interferon-γ (IFN-γ) and lipopolysaccharide (LPS) drives the activation of pulmonary macrophages and leads to the induction of pathogenic responses in the respiratory tract. Further, through gene array studies, we have shown that activation of macrophages by these molecules results in the selective expression of a number of ORs. In this study, we validated the expression of these ORs in mouse airway and pulmonary macrophages in response to IFN-γ and LPS (γ/LPS) stimulation, and further explored the effect of odorant stimulation on macrophage function. Methodology/Principal Findings OR expression in airway and pulmonary macrophages in response to IFN-γ, LPS or γ/LPS treatments was assessed by microarray and validated by q-PCR. OR expression (e.g. OR622) on macrophages was confirmed by visualization in immunofluoresence assays. Functional responses to odorants were assessed by quantifying inflammatory cytokine and chemokine expression using q-PCR and cell migration was assessed by a modified Boyden chamber migration assay. Our results demonstrate that eight ORs are expressed at basal levels in both airway and pulmonary macrophages, and that γ/LPS stimulation cooperatively increased this expression. Pulmonary macrophages exposed to the combined treatment of γ/LPS+octanal (an odorant) exhibited a 3-fold increase in MCP-1 protein production, compared to cells treated with γ/LPS alone. Supernatants from γ/LPS+octanal exposed macrophages also increased macrophage migration in vitro. Conclusions/Significance Eight different ORs are expressed at basal levels in pulmonary macrophages and expression is upregulated by the synergistic action of γ/LPS. Octanal stimulation further increased MCP-1 production and the motility of macrophages. Our results suggest that ORs may mediate macrophage function by regulating MCP-1 production and cell migration.
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Tadesse T, Derby CD, Schmidt M. Mechanisms underlying odorant-induced and spontaneous calcium signals in olfactory receptor neurons of spiny lobsters, Panulirus argus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2013; 200:53-76. [PMID: 24178131 DOI: 10.1007/s00359-013-0861-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 10/03/2013] [Accepted: 10/04/2013] [Indexed: 12/19/2022]
Abstract
We determined if a newly developed antennule slice preparation allows studying chemosensory properties of spiny lobster olfactory receptor neurons under in situ conditions with Ca(2+) imaging. We show that chemical stimuli reach the dendrites of olfactory receptor neurons but not their somata, and that odorant-induced Ca(2+) signals in the somata are sufficiently stable over time to allow stimulation with a substantial number of odorants. Pharmacological manipulations served to elucidate the source of odorant-induced Ca(2+) transients and spontaneous Ca(2+) oscillations in the somata of olfactory receptor neurons. Both Ca(2+) signals are primarily mediated by an influx of extracellular Ca(2+) through voltage-activated Ca(2+) channels that can be blocked by CoCl2 and the L-type Ca(2+) channel blocker verapamil. Intracellular Ca(2+) stores contribute little to odorant-induced Ca(2+) transients and spontaneous Ca(2+) oscillations. The odorant-induced Ca(2+) transients as well as the spontaneous Ca(2+) oscillations depend on action potentials mediated by Na(+) channels that are largely TTX-insensitive but blocked by the local anesthetics tetracaine and lidocaine. Collectively, these results corroborate the conclusion that odorant-induced Ca(2+) transients and spontaneous Ca(2+) oscillations in the somata of olfactory receptor neurons closely reflect action potential activity associated with odorant-induced phasic-tonic responses and spontaneous bursting, respectively. Therefore, both types of Ca(2+) signals represent experimentally accessible proxies of spiking.
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Affiliation(s)
- Tizeta Tadesse
- Neuroscience Institute and Department of Biology, Georgia State University, P.O. Box 5030, Atlanta, GA, 30302-5030, USA
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15
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Yazinski S, Gomez G. Time course of structural and functional maturation of human olfactory epithelial cells in vitro. J Neurosci Res 2013; 92:64-73. [PMID: 24123277 DOI: 10.1002/jnr.23296] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 08/07/2013] [Accepted: 08/12/2013] [Indexed: 11/06/2022]
Abstract
The unique ability of olfactory neurons to regenerate in vitro has allowed their use for the study of olfactory function, regeneration, and neurodegenerative disorders; thus, characterization of their properties is important. This present study attempts to establish the timeline of structural (protein expression) and functional (odorant sensitivity) maturation of human olfactory epithelial cells (hOE) in vitro using biopsy-derived cultured tissue. Cells were grown for 7 days; on each day, cells were tested for odorant sensitivity using calcium imaging techniques and then protein expression of each cell was tested using immunocytochemistry for proteins typically used for characterizing olfactory cells. Previous studies have shown that mature olfactory neurons in vitro attain a unique "phase-bright" morphology and express the olfactory marker protein (OMP). By day 3 in vitro, a variety of cells were odorant-sensitive, including both "phase-bright" and "phase-dark" cells that have previously been considered glial-like cells. The functional maturation of these hOEs appears to take place within 4 days. Interestingly, the emergence of an odorant sensitivity profile of both phase-bright and phase-dark cells preceded the expression of marker protein expression for OMP (which is expressed only by mature neurons in vivo). This structural maturation took 5 days, suggesting that the development of odorant sensitivity is not coincident with the expression of marker molecules that are hallmarks of structural maturation. These results have important implications for the use of hOEs as in vitro models of olfactory and neuronal function.
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Affiliation(s)
- Stepahnie Yazinski
- Department of Medicine, Massachusetts General Hospital, Charlestown, Massachusetts
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16
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Abstract
The central cell type involved in the initial perception of odors and transduction of the sensory signal are the olfactory receptor neurons (ORNs) located in the olfactory neuroepithelium of the nasal cavities. The olfactory epithelium is a unique system similar to the neuroepithelium of the embryonic neural tube, in which new neurons are continually generated throughout adult life. Olfactory neurons are derived from precursor cells that lie adjacent to the basal lamina of the olfactory epithelium; these precursor cells divide several times and their progeny differentiate into mature sensory neurons throughout life. Thus, the human olfactory epithelium has the potential to be used as a tool to examine certain human disorders resulting from abnormal development of the nervous system. This chapter presents methods for primary culture of human ORNs, which have been used successfully by multiple investigators. The protocol provides a consistent, heterogeneous cell population, which demonstrates functional responses to odorant mixtures and exhibits a complex neuronal phenotype, encompassing receptors and signaling pathways pertinent to both olfaction and other aspects of CNS function. These cultured neural cells exhibit neurotransmitter pathways important in a number of neuropsychiatric disorders, and the ability to culture cells from living human subjects provides a tool for assessing cellular neuropathology at the individual patient level.
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17
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Apuhan T, Yildirim YS, Simşek T, Yilmaz F, Yilmaz F. Concha bullosa surgery and the distribution of human olfactory neuroepithelium. Eur Arch Otorhinolaryngol 2012; 270:953-7. [PMID: 22941439 DOI: 10.1007/s00405-012-2173-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Accepted: 08/20/2012] [Indexed: 12/01/2022]
Abstract
In bullous middle turbinate surgery, controversy exists over which side of the bullous middle turbinate should be removed, as the distribution of human olfactory neuroepithelium is unclear. This study evaluated whether the middle turbinate tissue of patients undergoing endoscopic concha bullosa surgery contains functional olfactory epithelium. This prospective clinical study was conducted in tertiary referable center. It detected 70 conchae bullosa in 48 patients with sinonasal symptoms, who underwent paranasal computed tomography (CT) that showed pneumatization of the middle concha. All samples were obtained under general anesthesia. Three samples were obtained from each bullous middle turbinate: one each from the anterior, medial, and lateral portions. The mucosa from each sample was stained with olfactory marker protein (OMP). In total, 210 middle turbinate samples were taken from 48 patients during endoscopic surgery for conchae bullosa. The patients were 22 females and 26 males. Of the 70 conchae bullosa, OMP-stained nerve tissue was found in the lateral, anterior and medial aspects of 57 (81.4 %), 42 (60.0 %) and 23 (32.8 %) of the bullous middle turbinates, respectively. OMP-stained nerve tissue was found in 122 (58.1 %) of the 210 bullous middle turbinate tissue samples. OMP-stained nerve tissue was found on the lateral surface of the bullous middle turbinate more often than the medial surface. Therefore, during the concha bullosa surgery, OMP-stained nerve tissue found at least in the medial part of concha, suggested that the opening of the medial part of middle concha.
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Affiliation(s)
- Tayfun Apuhan
- Department of Otolaryngology, Faculty of Izzet Baysal Medicine, Abant Izzet Baysal University, Bolu, Turkey
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18
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Bryant B, Xu J, Audige V, Lischka FW, Rawson NE. Cellular basis for the olfactory response to nicotine. ACS Chem Neurosci 2010; 1:246-56. [PMID: 22777075 DOI: 10.1021/cn900042c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 02/16/2010] [Indexed: 01/24/2023] Open
Abstract
Smokers regulate their smoking behavior on the basis of sensory stimuli independently of the pharmacological effects of nicotine (Rose J. E., et al. (1993) Pharmacol., Biochem. Behav.44 (4), 891-900). A better understanding of sensory mechanisms underlying smoking behavior may help to develop more effective smoking alternatives. Olfactory stimulation by nicotine makes up a considerable part of the flavor of tobacco smoke, yet our understanding of the cellular mechanisms responsible for olfactory detection of nicotine remains incomplete. We used biophysical methods to characterize the nicotine sensitivity and response mechanisms of neurons from olfactory epithelium. In view of substantial differences in the olfactory receptor repertoire between rodent and human (Mombaerts P. (1999) Annu. Rev. Neurosci.22, 487-509), we studied biopsied human olfactory sensory neurons (OSNs), cultured human olfactory cells (Gomez G., et al. (2000) J. Neurosci. Res.62 (5), 737-749), and rat olfactory neurons. Rat and human OSNs responded to S(-)-nicotine with a concentration dependent influx of calcium and activation of adenylate cyclase. Some rat OSNs displayed some stereoselectivity, with neurons responding to either enantiomer alone or to both. Freshly biopsied and primary cultured human olfactory neurons were less stereoselective. Nicotinic cholinergic antagonists had no effect on the responses of rat or human OSNs to nicotine. Patch clamp recording of rat OSNs revealed a nicotine-activated, calcium-sensitive nonspecific cation channel. These results indicate that nicotine activates a canonical olfactory receptor pathway rather than nicotinic cholinergic receptors on OSNs. Further, because the nicotine-sensitive mechanisms of rodents appear generally similar to those of humans, this animal model is an appropriate one for studies of nicotine sensation.
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Affiliation(s)
- Bruce Bryant
- Monell Chemical Senses Center, Philadelphia, Pennsylvania
| | - Jiang Xu
- Monell Chemical Senses Center, Philadelphia, Pennsylvania
| | - Valery Audige
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania
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19
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The human olfactory mucosa. Eur Arch Otorhinolaryngol 2010; 266:1675-80. [PMID: 19714350 DOI: 10.1007/s00405-009-1073-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Accepted: 08/17/2009] [Indexed: 01/19/2023]
Abstract
Studies of the tissues of the human olfactory mucosa have been performed to investigate olfactory dysfunction and, more recently, olfactory mucosa has attracted a novel interest of investigators because it can be used as an early marker of neurodegenerative conditions of the brain and as a source of multipotent neural stem cells, with applications in regenerative medicine. The olfactory mucosa is readily available to the otolaryngologist, but the harvesting of this tissue must be safe, effective, and reliable, obtaining as little tissue as necessary, while avoiding unnecessary harm to the remaining olfactory tissue and function. The purpose of this review is to summarize the results of the most important studies and knowledge with regard to the human olfactory mucosa and its applications, emphasizing the issue of the distribution of the olfactory mucosa in the nasal cavities.
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20
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Gomez G, Celii A. The peripheral olfactory system of the domestic chicken: physiology and development. Brain Res Bull 2008; 76:208-16. [PMID: 18498933 DOI: 10.1016/j.brainresbull.2008.02.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 12/26/2007] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
Abstract
Olfaction is a ubiquitous sensory system found in all terrestrial vertebrates. Birds use olfaction for several important activities such as feeding and mating; thus, understanding bird biology would also require the systematic study olfaction. In addition, the olfactory system has several unique features that are useful for the study of nervous system function and development, including a large multigene family for olfactory receptor expression, peripheral neurons that regenerate, and a complex system for sensory innervation of the olfactory bulb. We focused on physiological, anatomical and behavioral approaches to study the chick olfactory neurons and the olfactory bulb. Chick olfactory neurons displayed some properties similar to those found in mature neurons of other vertebrate species, and other properties that were unique. Since information from these neurons is initially processed in the olfactory bulb, we also conducted preliminary studies on the developmental timeline of this structure and showed that glomerular structures are organized in ovo during a critical time period, during which embryonic chicks can form behavioral associations with odorants introduced in ovo. Lastly, we have shown that chick olfactory neurons can grow and mature in vitro, allowing their use in cell culture studies. These results collectively demonstrate some of the features of the olfactory system that are common to all vertebrates, and some that are unique to birds. These highlight the potential for the use of the physiology and development of the olfactory system as a model system for avian brain neurobiology.
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Affiliation(s)
- George Gomez
- Biology Department, University of Scranton, Scranton, PA 18510, USA.
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21
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Zhao K, Pribitkin EA, Cowart BJ, Rosen D, Scherer PW, Dalton P. Numerical modeling of nasal obstruction and endoscopic surgical intervention: outcome to airflow and olfaction. ACTA ACUST UNITED AC 2006; 20:308-16. [PMID: 16871935 DOI: 10.2500/ajr.2006.20.2848] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Mechanical obstruction of odorant flow to the olfactory neuroepithelium may be a primary cause of olfactory loss in nasal-sinus disease patients. Surgical removal of nasal obstruction may facilitate the recovery of olfactory ability. Unfortunately, quantifying the functional impact of nasal obstruction and subsequent surgical outcomes using acoustic rhinometry, rhinomanometry, or CT scans is inadequate. METHODS Using computational fluid dynamics (CFD) techniques, we can convert patient CT scans into anatomically accurate 3D numerical nasal models that can be used to predict nasal airflow and odorant delivery rates. These models also can be rapidly modified to reflect anatomic changes, e.g., surgical removal of polyps. RESULTS CFD modeling of one patient's nose pre- and postsurgery showed significant improvement in postsurgical ortho- and retronasal airflow and odorant delivery rate to olfactory neuroepithelium (> 1000 times), which correlated well with olfactory recovery. CONCLUSION This study has introduced a novel technique (CFD) to calculate nasal airflow dynamics and its effects on olfaction, nasal obstruction, and sinus disease. In the future, such techniques may provide a quantitative evaluation of surgical outcome and an important preoperative guide to optimize nasal airflow and odorant delivery.
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Affiliation(s)
- Kai Zhao
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, Pennsylvania, USA
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22
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Brauchi S, Cea C, Farias JG, Bacigalupo J, Reyes JG. Apoptosis induced by prolonged exposure to odorants in cultured cells from rat olfactory epithelium. Brain Res 2006; 1103:114-22. [PMID: 16814749 DOI: 10.1016/j.brainres.2006.05.072] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 05/12/2006] [Accepted: 05/12/2006] [Indexed: 11/26/2022]
Abstract
Multicellular organisms undergo programmed cell death (PCD) as a mechanism for tissue remodeling during development and tissue renewal throughout adult life. Overdose of some neuronal receptor agonists like glutamate can trigger a PCD process termed excitotoxicity in neurons of the central nervous system. Calcium has an important role in PCD processes, especially in excitotoxicity. Since the normal turnover of olfactory receptor neurons (ORNs) relies, at least in part, on an apoptotic mechanism and odor transduction in ORNs involves an increase in intracellular Ca2+ concentration ([Ca2+]i), we investigated the possibility that long-term exposures to odorants could trigger an excitotoxic process in olfactory epithelial cells (EC). We used single-cell [Ca2+]i determinations and fluorescence microscopy techniques to study the effects of sustained odorant exposures in olfactory EC in primary culture. Induction of PCD was evaluated successively by three independent criteria: (1) measurements of DNA fragmentation, (2) translocation of phosphatidylserine to the external leaflet of the plasma membrane, and (3) caspase-3 activation. Our results support the notion of an odorant-induced PCD in olfactory EC. This odorant-induced PCD was prevented by LY83583, an odorant response inhibitor, suggesting that ORNs are the main epithelial cell population undergoing odorant-induced PCD.
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Affiliation(s)
- Sebastian Brauchi
- Instituto de Quimica, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso, Chile
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23
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Abstract
Olfactory loss is a common age-related complaint that may be caused by changes in the anatomy of the structures required for olfaction (for example, loss of olfactory receptor cells) or in the environment surrounding the receptor cell (for example, altered nasal mucus composition). However, aging, as well as age-related diseases and medications, may also alter the distribution, density, or function of specific receptor proteins, ion channels, or signaling molecules that affect the ability of neural elements throughout the olfactory pathway to signal and process odorant information. Although a great deal has been learned about the prevalence and nature of age-related olfactory loss, we are just beginning to explore avenues to prevent or alleviate this sensory deficit. Some studies suggest that, rather than being a necessary outcome of aging, age-associated factors such as chronic diseases, medications, and dental and sinus problems are the primary culprits in causing olfactory impairment. This idea suggests optimism in that, as we address these other age-related health issues, the prevalence of olfactory loss will lessen as well.
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Affiliation(s)
- Nancy E Rawson
- Monell Chemical Senses Center, Philadelphia, PA 19104, USA.
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24
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Jung Y, Wirkus E, Amendola D, Gomez G. Characteristics of odorant elicited calcium fluxes in acutely-isolated chick olfactory neurons. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2005; 191:511-20. [PMID: 15838651 DOI: 10.1007/s00359-005-0617-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Revised: 01/24/2005] [Accepted: 02/05/2005] [Indexed: 10/25/2022]
Abstract
To understand avian olfaction, it is important to characterize the peripheral olfactory system of a representative bird species. This study determined the functional properties of olfactory receptor neurons of the chicken olfactory epithelium. Individual neurons were acutely isolated from embryonic day-18 to newborn chicks by dissection and enzymatic dissociation. We tested single olfactory neurons with behaviorally relevant odorant mixtures and measured their responses using ratiometric calcium imaging; techniques used in this study were identical to those used in other studies of olfaction in other vertebrate species. Chick olfactory neurons displayed properties similar to those found in other vertebrates: they responded to odorant stimuli with either decreases or increases in intracellular calcium, calcium increases were mediated by a calcium influx, and responses were reversibly inhibited by 100 microM L: -cis-diltiazem, 1 mM Neomycin, and 20 microM U73122, which are biochemical inhibitors of second messenger signaling. In addition, some cells showed a complex pattern of responses, with different odorant mixtures eliciting increases or decreases in calcium in the same cell. It appears that there are common features of odorant signaling shared by a variety of vertebrate species, as well as features that may be peculiar to chickens.
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Affiliation(s)
- Yewah Jung
- Biology Department, University of Scranton, Scranton, PA 18510, USA
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25
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Gomez G, Lischka FW, Haskins ME, Rawson NE. Evidence for multiple calcium response mechanisms in mammalian olfactory receptor neurons. Chem Senses 2005; 30:317-26. [PMID: 15800218 DOI: 10.1093/chemse/bji026] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Olfactory receptor neurons employ a diversity of signaling mechanisms for transducing and encoding odorant information. The simultaneous activation of subsets of receptor neurons provides a complex pattern of activation in the olfactory bulb that allows for the rapid discrimination of odorant mixtures. While some transduction elements are conserved among many species, some species-specificity occurs in certain features that may relate to their particular physiology and ecological niche. However, studies of olfactory transduction have been limited to a relatively small number of vertebrate and invertebrate species. To better understand the diversity and evolution of olfactory transduction mechanisms, we studied stimulus-elicited calcium fluxes in olfactory neurons from a previously unstudied mammalian species, the domestic cat. Isolated cells from cat olfactory epithelium were stimulated with odorant mixtures and biochemical agents, and cell responses were measured with calcium imaging techniques. Odorants elicited either increases or decreases in intracellular calcium; odorant-induced calcium increases were mediated either by calcium fluxes through the cell membrane or by mobilization of intracellular stores. Individual cells could employ multiple signaling mechanisms to mediate responses to different odorants. The physiological features of these olfactory neurons suggest greater complexity than previously recognized in the role of peripheral neurons in encoding complex odor stimuli. The investigation of novel and unstudied species is important for understanding the mechanisms of odorant signaling that apply to the olfactory system in general and suggests both broadly conserved and species-specific evolutionary adaptations.
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Affiliation(s)
- George Gomez
- Biology Department, University of Scranton, Scranton, PA 18510, USA
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26
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Abstract
Olfaction begins with the transduction of the information carried by odorants into electrical signals in olfactory receptor cells (ORCs). The binding of odor molecules to specific receptor proteins on the ciliary surface of ORCs induces the receptor potentials. This initial excitation causes a slow and graded depolarizing voltage change, which is encoded into a train of action potentials. Action potentials of ORCs are generated by voltage-gated Na+ currents and T-type Ca2+ currents in the somatic membrane. Isolated ORCs, which have lost their cilia during the dissociation procedure, are known to exhibit spike frequency accommodation by injecting the steady current. This raises the possibility that somatic ionic channels in ORCs may serve for odor adaptation at the level of spike encoding, although odor adaptation is mainly accomplished by the ciliary transduction machinery. This review discusses current knowledge concerning the mechanisms of spike generation in ORCs. It also reviews how neurotransmitters and hormones modulate ionic currents and action potentials in ORCs.
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Affiliation(s)
- Kenji Narusuye
- Department of Physiology, School of Medicine, Fujita Health University, 1-98 Dengakugakubo, Kutsukakechou, Toyoake, Aichi 470-1192, Japan
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Abstract
The olfactory system sits at the interface of the environment and the nervous system and is responsible for correctly coding sensory information from thousands of odorous stimuli. Many theories existed regarding the signal transduction mechanism that mediates this difficult task. The discovery that odorant transduction utilizes a unique variation (a novel family of G protein-coupled receptors) based upon a very common theme (the G protein-coupled adenylyl cyclase cascade) to accomplish its vital task emphasized the power and versatility of this motif. We now must understand the downstream consequences of this cascade that regulates multiple second messengers and perhaps even gene transcription in response to the initial interaction of ligand with G protein-coupled receptor.
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Affiliation(s)
- Gabriele V Ronnett
- Departments of Neuroscience and Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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Reisert J, Matthews HR. Simultaneous recording of receptor current and intraciliary Ca2+ concentration in salamander olfactory receptor cells. J Physiol 2001; 535:637-45. [PMID: 11559763 PMCID: PMC2278810 DOI: 10.1111/j.1469-7793.2001.00637.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. The suction pipette technique was combined with laser spot fluorescence microscopy to record simultaneously odour-induced current responses and intraciliary Ca2+ concentration from isolated salamander olfactory receptor cells loaded with the fluorescent Ca2+ indicator fluo-3. 2. When exposed for 1 s to increasing odour concentrations both the suction pipette current and fluo-3 fluorescence increased dynamically, rising with a similar time course. Thereafter, the fluorescence signal decayed more slowly, outlasting the current response by 0.56 +/- 0.12 s. 3. The fluo-3 fluorescence evoked by progressively increasing odour concentrations varied in an approximately linear manner with the magnitude of the suction pipette current. 4. Prolonged odour stimulation evoked synchronous oscillations in both suction pipette current and intraciliary calcium concentration with a mean period of 4.5 +/- 0.3 s. 5. When external Na+ was omitted from the stimulating solution the oscillation period for both the current and fluorescence signals was lengthened by a factor of 1.9 +/- 0.2 in comparison with the oscillation period when stimulated in Ringer solution. 6. These results support the currently accepted mechanism for Ca2+ homeostasis within the olfactory cilia, and are consistent with the notion that the oscillations induced by prolonged odour exposure represent the coupled oscillation of Ca2+ and cyclic nucleotide concentrations.
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Affiliation(s)
- J Reisert
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
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Abstract
The main and accessory olfactory systems have received considerable attention on the part of scientists and clinicians during the last decade, largely because of (a) quantum advances in understanding their genetically expressed receptor mechanisms, (b) evidence that their receptor cells undergo neurogenesis and both programmed and induced cell death, and (c) important technical and practical developments in psychophysical measurement. The latter developments have led to the proliferation of standardized olfactory testing in laboratories and clinics, and to the discovery that smell loss is among the first signs of a number of neurodegenerative diseases, including Alzheimer's disease and idiopathic Parkinson's disease. Recent controversial claims that humans possess a functioning vomeronasal system responsive to "pheromones" has added further interest in intranasal chemoreception. This review focuses on recent progress made in understanding olfactory function, emphasizing transduction, measurement, and clinical findings.
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Affiliation(s)
- R L Doty
- Smell and Taste Center, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA.
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Gomez G, Rawson NE, Hahn CG, Michaels R, Restrepo D. Characteristics of odorant elicited calcium changes in cultured human olfactory neurons. J Neurosci Res 2000; 62:737-49. [PMID: 11104513 DOI: 10.1002/1097-4547(20001201)62:5<737::aid-jnr14>3.0.co;2-a] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
An important step in establishing and utilizing a cell culture system for the in vitro study of olfaction is assessing whether the cultured cells possess physiological properties similar to those of mature olfactory neurons. Various investigators have successfully established proliferating cell lines from olfactory tissue, but few have demonstrated the characteristics of odor sensitivity of these cells. We successfully established cultured cell lines from adult human olfactory tissue obtained using an olfactory biopsy procedure and measured their ability to respond to odor stimulation using calcium imaging techniques. A subset of the human olfactory cells in culture displayed a distinct morphology and specifically expressed immunocytochemical markers characteristic of mature human olfactory neurons such as OMP, G(olf), NCAM and NST. Under defined growth conditions, these cultured cells responded to odorant mixes that have been previously shown to elicit intracellular calcium changes in acutely-isolated human olfactory neurons. These odorant-elicited calcium responses displayed characteristics similar to those found in mature human olfactory neurons. First, cultured cells responded with either increases or decreases in intracellular calcium. Second, increases in calcium were abolished by removal of extracellular calcium. Third, inhibitors of the olfactory signal transduction cascades reversibly blocked these odorant-elicited intracellular calcium changes. Our results demonstrate that cultures of adult human olfactory cells established from olfactory biopsies retain some of the in vivo odorant response characteristics of acutely isolated cells from the adult olfactory epithelium. This work has important ramifications for investigation of olfactory function and dysfunction using biopsy procedures and in vitro assays of odor sensitivity.
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Affiliation(s)
- G Gomez
- Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104-3308, USA.
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Gomez G, Rawson NE, Cowart B, Lowry LD, Pribitkin EA, Restrepo D. Modulation of odor-induced increases in [Ca(2+)](i) by inhibitors of protein kinases A and C in rat and human olfactory receptor neurons. Neuroscience 2000; 98:181-9. [PMID: 10858624 DOI: 10.1016/s0306-4522(00)00112-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Protein kinases A and C have been postulated to exert multiple effects on different elements of signal transduction pathways in olfactory receptor neurons. However, little is known about the modulation of olfactory responses by protein kinases in intact olfactory receptor neurons. To further elucidate the details of the modulation of odorant responsiveness by these protein kinases, we investigated the action of two protein kinase inhibitors: H89, an inhibitor of protein kinase A, and N-myristoylated EGF receptor, an inhibitor of protein kinase C, on odorant responsiveness in intact olfactory neurons. We isolated individual olfactory neurons from the adult human and rat olfactory epithelium and measured responses of the isolated cells to odorants or biochemical activators that have been shown to initiate cyclic AMP or inositol 1,4,5-trisphospate production in biochemical preparations. We employed calcium imaging techniques to measure odor-elicited changes in intracellular calcium that occur over several seconds. In human olfactory receptor neurons, the protein kinase A and C inhibitors affected the responses to different sets of odorants. In rats, however, the protein kinase C inhibitor affected responses to all odorants, while the protein kinase A inhibitor had no effect. In both species, the effect of inhibition of protein kinases was to enhance the elevation and block termination of intracellular calcium levels elicited by odorants. Our results show that protein kinases A and C may modulate odorant responses of olfactory neurons by regulating calcium fluxes that occur several seconds after odorant stimulation. The effects of protein kinase C inhibition are different in rat and human olfactory neurons, indicating that species differences are an important consideration when applying data from animal studies to apply to humans.
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Affiliation(s)
- G Gomez
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA.
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Vogl A, Noé J, Breer H, Boekhoff I. Cross-talk between olfactory second messenger pathways. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:4529-35. [PMID: 10880977 DOI: 10.1046/j.1432-1327.2000.01503.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The second messengers 3'-5'-cyclic-monophosphate (cAMP) and inositol 1,4,5-trisphosphate (InsP3) have been implicated in olfactory signal transduction in various species. The results of the present study provide evidence that the two olfactory second messenger pathways in rat olfactory neurons do not work independently but rather show a functional antagonism: whereas inhibition of phospholipase C (PLC) in isolated olfactory cilia by U-73122 led to an augmentation of odor-induced cAMP signaling, activation of the phosphoinositol pathway resulted in attenuation of odor-induced cAMP formation. Furthermore, this study indicates that elevated cAMP levels cause suppression of odor-induced InsP3 signaling, whereas inhibition of adenylate cyclase (AC) by cisN-(2-phenylcyclopentyl)azacylotridec-1-en-2-amine (MDL-12,330 A) results in potentiation of odor-induced InsP3 formation. Concerning the molecular mechanism involved in cross-interaction, the experimental data indicate that the observed antagonism of elevated cAMP is based on inhibition of PLC activation rather than on stimulation of InsP3 degradation. As blockage of the endogenous protein kinase A (PKA) prevented the inhibitory effect of cAMP, the suppression of odor-induced InsP3 signaling by cAMP may be mediated by a PKA-controlled reaction.
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Affiliation(s)
- A Vogl
- University Stuttgart-Hohenheim, Institute of Physiology, Stuttgart, Germany
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Leopold DA, Hummel T, Schwob JE, Hong SC, Knecht M, Kobal G. Anterior distribution of human olfactory epithelium. Laryngoscope 2000; 110:417-21. [PMID: 10718430 DOI: 10.1097/00005537-200003000-00016] [Citation(s) in RCA: 205] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES/HYPOTHESIS To functionally investigate the distribution of the olfactory epithelium in humans by means of the electro-olfactogram (EOG) and anatomically located biopsy specimens. STUDY DESIGN Prospective, nonrandomized, investigational. METHODS Supra-threshold EOG recordings were made on 12 healthy, trained volunteers (6 women, 6 men; age range, 21-48 y). Vanillin was used as the stimulus, since it exclusively excites olfactory receptor neurons. The EOG was recorded with tubular electrodes that were placed using thin-fiber endoscopic guidance. Biopsy specimens were obtained of anterosuperior nasal cavity mucosa in the same regions as the positive EOGs in 15 smell-tested patients (7 women, 8 men; age range, 22-60 y) during routine nasal and sinus surgery. This biopsied tissue was histologically processed and stained for olfactory and neural proteins. RESULTS Viable responses to EOG testing were obtained in 7 of 12 subjects. In these seven subjects it was possible to identify nine sites above or below the anterior middle turbinate insertion where EOGs were obtained. The biopsy results showed mature olfactory receptor neurons in this same area. CONCLUSIONS Human olfactory epithelium appears to be distributed more anteriorly than previously assumed.
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Affiliation(s)
- D A Leopold
- Department of Otolaryngology-Head and Neck Surgery, University of Nebraska, Omaha 68198-1225, USA
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Okada Y, Fujiyama R, Miyamoto T, Sato T. Comparison of a Ca(2+)-gated conductance and a second-messenger-gated conductance in rat olfactory neurons. J Exp Biol 2000; 203:567-73. [PMID: 10637185 DOI: 10.1242/jeb.203.3.567] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effect of a rise in intracellular Ca(2+) concentration was analyzed in isolated rat olfactory neurons using a whole-cell patch-clamp technique. Intracellular dialysis of 1 mmol l(−)(1) Ca(2+) in a standard-K(+), low-Cl(−) internal solution (E(Cl)=−69 mV) from the patch pipette into the olfactory neurons induced a sustained outward current of 49+/−5 pA (N=13) at −50 mV in all the cells examined. The outward currents were inhibited by external application of 100 micromol l(−)(1) 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB). External application of a Ca(2+) ionophore, 3 micromol l(−)(1) ionomycin, induced an inward current in three of eight cells whose voltages were clamped using the gramicidin-perforated technique, but ionomycin elicited an outward current in the other five cells, suggesting that natural intracellular Cl(−) concentration in the olfactory neurons was heterogeneous. While intracellular dialysis of 50 micromol l(−)(1) inositol 1,4,5-trisphosphate (1,4,5-InsP(3)) in the standard-K(+), low-Cl(−) internal solution induced the NPPB-sensitive outward current in 31 % of cells, and 500 micromol l(−)(1) cAMP induced it in 21 % of cells, a large proportion of the cells displayed an inward current in response to 1,4,5-InsP(3) and cAMP. The results suggest that 1,4,5-InsP(3) and cAMP can elicit Ca(2+)-dependent Cl(−) conductance and Ca(2+)-independent cation conductance in rat olfactory neurons.
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Affiliation(s)
- Y Okada
- Department of Physiology, Nagasaki University School of Dentistry, Nagasaki 852-8588, Japan.
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Miwa N, Kobayashi M, Takamatsu K, Kawamura S. Purification and molecular cloning of a novel calcium-binding protein, p26olf, in the frog olfactory epithelium. Biochem Biophys Res Commun 1998; 251:860-7. [PMID: 9791000 DOI: 10.1006/bbrc.1998.9571] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Olfactory adaptation requires the change of intracellular calcium concentration during stimuli. To contribute in the study of the molecular mechanism of calcium-dependent regulations in olfactory receptor cells, we isolated a novel 26-kDa Ca2+-binding protein named p26olf from the frog olfactory epithelium after four chromatographical steps. Based on the partial amino acid sequences of the proteolysed fragments of p26olf, we obtained a cDNA clone that encodes p26olf. The analysis of its amino acid sequence revealed that p26olf consists of two S-100-like regions aligned sequentially with a calculated molecular mass of 24,493. Northern blot analysis showed that p26olf is expressed in the frog olfactory epithelium and also in other tissues. Immunoreactivity against p26olf was detected in the cilia layer of the olfactory epithelium. These results suggest that p26olf is a dimeric form of S-100 proteins and is involved in the olfactory transduction or adaptation.
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Affiliation(s)
- N Miwa
- Department of Physiology, Keio University School of Medicine, Shinano-machi 35, Tokyo, Shinjyuku-ku, 160, Japan
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36
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Spielman AI. Chemosensory function and dysfunction. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 1998; 9:267-91. [PMID: 9715366 DOI: 10.1177/10454411980090030201] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Taste and smell are fundamental sensory systems essential in nutrition and food selection, for the hedonic and sensory experience of food, for efficient metabolism, and, in general, for the maintenance of a good quality of life. The gustatory and olfactory systems demonstrate a diversity of transduction mechanisms, and during the last decade, considerable progress has been made toward our understanding of the basic mechanisms of taste and smell. Understanding normal chemosensory function helps clarify the molecular events that underlie taste and smell disorders. At least 2,000,000 Americans suffer from chemosensory disorders--a number that is likely to grow as the aging segment of the population increases. Smell disorders are more frequent than taste disturbances, due to the vulnerability and anatomical distinctiveness of the olfactory system, and because a decline in olfactory function is part of the normal aging process. Common gustatory and olfactory complaints are due to a number of medications, to upper respiratory infections, to nasal and paranasal sinus diseases, and to damage to peripheral nerves supplying taste and smell. Most chemosensory complaints have an identifiable cause. Although diagnosis of taste and smell disorders has improved considerably over the last two decades, treatment of these disorders is still limited to conditions with discernible and reversible causes. Future research is needed for a better understanding of chemosensory mechanisms, establishing improved diagnostic procedures, and disseminating knowledge on chemosensory disorders among practitioners and the general public.
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Affiliation(s)
- A I Spielman
- Basic Science Division, New York University College of Dentistry, New York 10010, USA
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37
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Abstract
Considerable progress has been made in the understanding of transduction mechanisms in olfactory receptor neurons (ORNs) over the last decade. Odorants pass through a mucus interface before binding to odorant receptors (ORs). The molecular structure of many ORs is now known. They belong to the large class of G protein-coupled receptors with seven transmembrane domains. Binding of an odorant to an OR triggers the activation of second messenger cascades. One second messenger pathway in particular has been extensively studied; the receptor activates, via the G protein Golf, an adenylyl cyclase, resulting in an increase in adenosine 3',5'-cyclic monophosphate (cAMP), which elicits opening of cation channels directly gated by cAMP. Under physiological conditions, Ca2+ has the highest permeability through this channel, and the increase in intracellular Ca2+ concentration activates a Cl- current which, owing to an elevated reversal potential for Cl-, depolarizes the olfactory neuron. The receptor potential finally leads to the generation of action potentials conveying the chemosensory information to the olfactory bulb. Although much less studied, other transduction pathways appear to exist, some of which seem to involve the odorant-induced formation of inositol polyphosphates as well as Ca2+ and/or inositol polyphosphate -activated cation channels. In addition, there is evidence for odorant-modulated K+ and Cl- conductances. Finally, in some species, ORNs can be inhibited by certain odorants. This paper presents a comprehensive review of the biophysical and electrophysiological evidence regarding the transduction processes as well as subsequent signal processing and spike generation in ORNs.
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Affiliation(s)
- D Schild
- Physiologisches Institut, Universität Göttingen, Germany
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38
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Wysocki CJ, Dalton P, Brody MJ, Lawley HJ. Acetone odor and irritation thresholds obtained from acetone-exposed factory workers and from control (occupationally unexposed) subjects. AMERICAN INDUSTRIAL HYGIENE ASSOCIATION JOURNAL 1997; 58:704-12. [PMID: 9342830 DOI: 10.1080/15428119791012342] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Sensitivity of olfaction (smell) and chemesthesis (irritation) was evaluated for 2-propanone (acetone) and 1-butanol in acetone-exposed workers (AEW; N = 32) during a workday and unexposed subjects (microES; N = 32). Irritation sensitivity was assessed using a method that relies on the ability of individuals to localize irritants on the body. When a volatile compound is inhaled into one nostril and air into the other, the stimulated side can be determined (lateralized) only after the concentration reaches a level that stimulates the trigeminal nerve (irritation); compounds stimulating olfaction alone cannot be lateralized. Intranasal lateralization thresholds offer an objective measure of sensory irritation elicited by volatile compounds. Test results indicated that neither olfactory nor lateralization thresholds for butanol differed between AEW and microES. Olfactory thresholds to acetone in AEW (855 ppm) were elevated relative to those of microES (41 ppm), as were lateralization thresholds (36,669 ppm and 15,758 ppm, respectively). Within AEW, level of occupational exposure was not correlated with thresholds. Other measures revealed that microES used more irritation descriptors than did AEW on trials where the acetone concentration was below the lateralization threshold. This is noteworthy because microES received lower concentrations of acetone to evaluate than did AEW. These results suggest that exposures to acetone induce changes in acetone sensitivity that are specific to acetone. The acetone concentrations eliciting sensory irritation using the lateralization technique were all well above current occupational exposure standards. The current study indicates that acetone is a weak sensory irritant and that sensory adaptation is an important factor affecting its overall irritancy.
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Affiliation(s)
- C J Wysocki
- Monell Chemical Senses Center, Philadelphia, PA 19104, USA.
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39
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Bruch RC, Kang J, Moore ML, Medler KF. Protein kinase C and receptor kinase gene expression in olfactory receptor neurons. JOURNAL OF NEUROBIOLOGY 1997; 33:387-94. [PMID: 9322156 DOI: 10.1002/(sici)1097-4695(199710)33:4<387::aid-neu4>3.0.co;2-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Recent biochemical evidence indicates that protein kinase C (PKC) and G-protein-coupled receptor kinases (GRKs) are involved in olfactory signal termination and desensitization. The polymerase chain reaction (PCR) was used to investigate the expression of PKC and GRK genes in olfactory tissue and in isolated olfactory receptor neurons from channel catfish (Ictalurus punctatus). Sequence analysis of cloned PKC PCR products showed that the alpha, beta, delta, epsilon, and theta isotypes were expressed in olfactory tissue. Sequence analysis of PCR products obtained from isolated olfactory receptor neurons showed that PKC beta and PKC delta were expressed in the receptor cells. A 600-bp GRK PCR product was obtained from isolated olfactory neurons that shared 86% and 92% amino acid sequence identity to the mammalian beta-adrenergic receptor kinase gene products beta ARK1 and beta ARK2, respectively. Go6976, a specific inhibitor of calcium-regulated PKC activity, completely inhibited odorant-stimulated PKC activity in isolated olfactory cilia. This result suggested that odorant-stimulated PKC activity is mediated by the calcium-sensitive PKC beta isotype. Taken together, these results are consistent with the conclusion that PKC beta and beta ARK mediate odorant receptor phosphorylation and olfactory signal termination.
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Affiliation(s)
- R C Bruch
- Department of Zoology and Physiology, Louisiana State University, Baton Rouge 70803, USA
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40
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Calcium entry through cyclic nucleotide-gated channels in individual cilia of olfactory receptor cells: spatiotemporal dynamics. J Neurosci 1997. [PMID: 9151731 DOI: 10.1523/jneurosci.17-11-04136.1997] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Transient elevations of intracellular Ca2+ play an important role in regulating the sensitivity of olfactory transduction, but such elevations have not been demonstrated in the olfactory cilia, which are the site of primary odor transduction. To begin to understand Ca2+ signaling in olfactory cilia, we used high-resolution imaging techniques to study the Ca2+ transients that occur in salamander olfactory receptor neurons (ORNs) as a result of cyclic nucleotide-gated (CNG) channel activation. To visualize ciliary Ca2+ signals, we loaded ORNs with the Ca2+ indicator dye Fluo-3 AM and measured fluorescence with a laser scanning confocal microscope. Application of the phosphodiesterase inhibitor IBMX increased fluorescence in the cilia and other neuronal compartments; the ciliary signal occurred first and was more transient. This signal could be abolished by lowering external Ca2+ or by applying LY83583, a potent blocker of CNG channels, indicating that Ca2+ entry through CNG channels was the primary source of fluorescence increases. Direct activation of CNG channels with low levels of 8-Br-cGMP (1 microM) led to tonic Ca2+ signals that were restricted locally to the cilia and the dendritic knob. Elevated external K+, which depolarizes cell membranes, increased fluorescence signals in the cell body and dendrite but failed to increase ciliary Ca2+ fluorescence. The results demonstrate the existence and spatiotemporal properties of Ca2+ transients in individual olfactory cilia and implicate CNG channels as a major pathway for Ca2+ entry into ORN cilia during odor transduction.
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41
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Leinders-Zufall T, Rand MN, Shepherd GM, Greer CA, Zufall F. Calcium entry through cyclic nucleotide-gated channels in individual cilia of olfactory receptor cells: spatiotemporal dynamics. J Neurosci 1997; 17:4136-48. [PMID: 9151731 PMCID: PMC6573532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/1997] [Revised: 03/11/1997] [Accepted: 03/18/1997] [Indexed: 02/04/2023] Open
Abstract
Transient elevations of intracellular Ca2+ play an important role in regulating the sensitivity of olfactory transduction, but such elevations have not been demonstrated in the olfactory cilia, which are the site of primary odor transduction. To begin to understand Ca2+ signaling in olfactory cilia, we used high-resolution imaging techniques to study the Ca2+ transients that occur in salamander olfactory receptor neurons (ORNs) as a result of cyclic nucleotide-gated (CNG) channel activation. To visualize ciliary Ca2+ signals, we loaded ORNs with the Ca2+ indicator dye Fluo-3 AM and measured fluorescence with a laser scanning confocal microscope. Application of the phosphodiesterase inhibitor IBMX increased fluorescence in the cilia and other neuronal compartments; the ciliary signal occurred first and was more transient. This signal could be abolished by lowering external Ca2+ or by applying LY83583, a potent blocker of CNG channels, indicating that Ca2+ entry through CNG channels was the primary source of fluorescence increases. Direct activation of CNG channels with low levels of 8-Br-cGMP (1 microM) led to tonic Ca2+ signals that were restricted locally to the cilia and the dendritic knob. Elevated external K+, which depolarizes cell membranes, increased fluorescence signals in the cell body and dendrite but failed to increase ciliary Ca2+ fluorescence. The results demonstrate the existence and spatiotemporal properties of Ca2+ transients in individual olfactory cilia and implicate CNG channels as a major pathway for Ca2+ entry into ORN cilia during odor transduction.
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Affiliation(s)
- T Leinders-Zufall
- Section of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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42
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Rawson NE, Gomez G, Cowart B, Brand JG, Lowry LD, Pribitkin EA, Restrepo D. Selectivity and response characteristics of human olfactory neurons. J Neurophysiol 1997; 77:1606-13. [PMID: 9084623 DOI: 10.1152/jn.1997.77.3.1606] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Transduction mechanisms were investigated in human olfactory neurons by determining characteristics of odorant-induced changes in intracellular calcium concentration ([Ca2+]i). Olfactory neurons were freshly isolated from nasal biopsies, allowed to attach to coverslips, and loaded with the calcium-sensitive indicator fura-2. Changes in [Ca2+]i were studied in response to exposure to individual odors, or odorant mixtures composed to distinguish between transduction pathways mediated by adenosine 3'5'-monophosphate (cAMP; mix A) or inositol 1,4,5-trisphosphate (InsP3; mix B). Overall, 52% of biopsies produced one or more odorant-responsive olfactory neurons, whereas 24% of all olfactory neurons tested responded to odorant exposure with a change in [Ca2+]i. As in olfactory neurons from other species, the data suggest that odorant exposure elicited calcium influx via second-messenger pathways involving cAMP or InsP3. Unlike olfactory neurons from other species that have been tested, some human olfactory neurons responded to odorants with decreases in [Ca2+]i. Also in contrast with olfactory neurons from other species, human olfactory neurons were better able to discriminate between odorant mixtures in that no neuron responded to more than one type of odor or mixture. These results suggest the presence of a previously unreported type of olfactory transduction mechanism, and raise the possibility that coding of odor qualities in humans may be accomplished to some degree differently than in other vertebrates, with the olfactory neuron itself making a greater contribution to the discrimination process.
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Affiliation(s)
- N E Rawson
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, USA
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43
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Gomez G, Restrepo D, Rawson N, Lowry LD, Keane WM, Rothstein JL. Induction of differentiation of human olfactory neuroblastoma cells into odorant-responsive cells. Neuroscience 1996; 74:567-77. [PMID: 8865206 DOI: 10.1016/0306-4522(96)00143-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Olfactory neuroblastoma is a rare malignancy of the olfactory mucosa that may be derived from the olfactory epithelium. To characterize this tumor, we cultured olfactory neuroblastoma cells in the presence or absence of growth factors (transforming growth factor alpha and basic fibroblast growth factor) known to affect olfactory tissue and assessed their responsiveness to known odorants by measuring changes in intracellular calcium. Untreated cells did not respond to odorants. Basic fibroblast growth factor treatment had cytotoxic effects, and treated cells did not respond to odorants. Transforming growth factor alpha treatment resulted in the induction of odor responsiveness in these cells. Cells responded to odorants at 100 nM to 100 microM concentrations and responded with both increases and decreases in intracellular calcium. Increases in intracellular calcium were mediated by a calcium influx and were reversibly blocked by compounds known to inhibit second messenger pathways in olfactory receptor neurons. The calcium responses of the olfactory neuroblastoma cells were thus specific to the odorants and similar to those found in olfactory receptor neurons. The results support the notion that olfactory neuroblastoma cells may be of olfactory origin and thus they can be used as a model cell line to study human olfaction.
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Affiliation(s)
- G Gomez
- Monell Chemical Senses Center, Philadelphia, PA 19104, USA
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44
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Abstract
Olfactory receptor neurons respond to odorants with G-protein mediated increases in the concentration of cyclic adenosine 3',5'-monophosphate (cAMP) and/or inositol 1,4,5-trisphospahte (InsP3). These two second messengers directly regulate opening of cAMP- and InsP3-regulated conductances localized to the apical transduction compartments of the cell (cilia and olfactory knob). In the presence of physiological concentrations of extracellular Ca2+, these second messenger regulated conductances mediate influx of Ca2+ into the olfactory neuron resulting in large, localized increases in intracellular Ca2+ ([Ca2+]i). A significant advance in our understanding of the molecular mechanisms of olfaction is the recent realization that this increase in [Ca2+]i plays an important role as a "third messenger" in olfactory transduction. Second messenger dependent increases in [Ca2+]i cause opening of ciliary Ca(2+)-activated Cl-, cation and/ or K+ channels that can carry a large percentage of the generator current, thus amplifying the signal substantially. As a result of this sequence of events, the generator potential in olfactory neurons can be depolarizing, leading to excitation of the neuron, or hyperpolarizing, leading to suppression of basal action potential firing rate. This dual effect of odorants on olfactory neurons may play an important role in quality coding and in the ability to detect low concentrations of odorants, particularly in complex mixtures.
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Affiliation(s)
- D Restrepo
- Monell Chemical Senses Center, University of Pennsylvania, Philadelphia, 19104, USA.
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45
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Abstract
Olfactory stimuli (odorants) are detected and recognized by binding to receptors belonging to the G-protein-coupled receptor superfamily. The binding of odorants to some receptors stimulates the activity of an odorant-sensitive phospholipase C (PLC) thereby generating the second messengers inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). IP3 plays a key role in membrane depolarization by binding to a receptor that is itself a cation channel. The formation of DAG is expected to stimulate the activity of protein kinase C (PKC). PKC, together with G-protein-coupled receptor kinases, mediates signal termination by phosphorylation of odorant receptors and possibly other substrates. This review summarizes recent evidence regarding the role of phosphoinositide-derived second messengers in the molecular events underlying olfactory signaling. In addition, the role of calcium as a "third messenger" that provides a mechanism for interaction between phosphoinositide second messengers and components of the cyclic AMP signaling pathway is also discussed.
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Affiliation(s)
- R C Bruch
- Department of Zoology and Physiology, Louisiana State University, Baton Rouge 70803, USA
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46
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Yamagishi M, Takami S, Getchell TV. Ontogenetic expression of spot 35 protein (calbindin-D28k) in human olfactory receptor neurons and its decrease in Alzheimer's disease patients. Ann Otol Rhinol Laryngol 1996; 105:132-9. [PMID: 8659934 DOI: 10.1177/000348949610500208] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Expression of a calcium-binding protein, spot 35 protein (S-35, calbindin-D28k), was investigated immunohistochemically in the human olfactory mucosa of patients who ranged in age from 16 weeks of fetal development to 98 years old, including some with Alzheimer's disease (AD). S-35 immunoreactivity was observed clearly in olfactory receptor neurons (ORNs) and olfactory nerve bundles that were identified previously with antibodies to olfactory marker protein (OMP) and neuron-specific enolase (NSE). Throughout all ages, the mean number of ORNs immunoreactive for OMP did not change significantly, whereas the mean number of NSE- and S-35-immunoreactive ORNs declined markedly in the postnatal infant, young, and old patients when compared with that of the prenatal fetuses. S-35-immunoreactive ORNs decreased significantly in AD patients when compared with AD control patients. These results indicate that ORNs in humans express S-35 and that there is an age-related trend in the expression of S-35. Furthermore, the marked decrease of S-35 expression in ORNs of AD patients suggests that cell excitability associated with calcium ions and cell protective function against overload of intracellular calcium ions decline in these patients.
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Affiliation(s)
- M Yamagishi
- Department of Surgery, University of Kentucky College of Medicine, Lexington 40536-0084, USA
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Rawson NE, Brand JG, Cowart BJ, Lowry LD, Pribitkin EA, Rao VM, Restrepo D. Functionally mature olfactory neurons from two anosmic patients with Kallmann syndrome. Brain Res 1995; 681:58-64. [PMID: 7552292 DOI: 10.1016/0006-8993(95)00283-v] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Patients with Kallmann syndrome (KS) exhibit hypogonadotropic hypogonadism and anosmia [Kallmann et al., Am. J. Mental Def., 48 (1944) 203-236] secondary to failure of gonadotropin-releasing hormone (GnRH)-producing neurons to migrate from the olfactory placode to the brain, and to agenesis of the olfactory bulbs. It has been hypothesized that olfactory neurons (ON) from individuals with KS are immature partly on the basis of studies in animals showing that lack of synaptic connection of ON with the olfactory bulb results in expression of immature ON [Schwob et al., J. Neurosci., 12 (1979) 880-883]. To test this assumption, we obtained olfactory tissue samples from two males diagnosed with KS on the basis of medical history and MRI studies. Both patients were anosmic. The functioning of cells isolated from biopsies taken from the upper middle turbinate and septum was studied by measuring changes in intracellular Ca2+ concentration ([Cai]) using dual excitation fluorescence microscopy. Biopsies from both patients yielded cells that morphologically appeared to be ON. Seven of 16 cells that morphologically resembled ON responded with a change in [Cai] upon stimulation with an odorant mixture. These studies show that at least some ON in KS individuals are functionally mature and suggest that complete development of the olfactory bulbs is not required for differentiation of mature human ON.
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Affiliation(s)
- N E Rawson
- Monell Chemical Senses Center, Philadelphia, PA 19104-3308, USA
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