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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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2
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Donadoni M, Kaminski R, Liao S, Al Janabi S, Margolskee RF, Ozdener MH, Sariyer IK. Coronavirus infection in chemosensory cells. J Neurovirol 2023; 29:35-44. [PMID: 36719595 PMCID: PMC9888344 DOI: 10.1007/s13365-023-01117-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 01/11/2023] [Accepted: 01/21/2023] [Indexed: 02/01/2023]
Abstract
Clinical manifestations of human coronavirus (HCoV)-related diseases are mostly related to the respiratory system, although secondary complications such as headache, anosmia, ageusia, and myalgia have been reported. HCoV infection and replication in chemosensory cells associated with ageusia and anosmia is poorly understood. Here, we characterized HCoV-OC43 and SARS-CoV-2 infection in two types of chemosensory cells, olfactory and taste cells, with their unique molecular and histological characteristics. We first assessed HCoV-OC43 infection in in vitro cultured human olfactory epithelial cells (hOECs) and fungiform taste papilla (HBO) cells. Interestingly, while both cell types were susceptible to HCoV-OC43 infection, viral replication rates were significantly reduced in HBO cells compared to hOECs. More interestingly, while culture media from hOECs was able to produce secondary infection in Vero cells, there was very limited secondary infection from HBO cells, suggesting that HBO cells may not be able to release infectious virus. On the other hand, unlike HCoV-OC43, SARS-CoV-2 showed comparable levels of viral infection rates in both hOECs and HBO cells. Furthermore, our RT-qPCR-based gene array studies revealed that several key genes involved in taste and olfactory functions were significantly altered by SARS-CoV-2 infection. These results may suggest a possible mechanism associated with chemosensory symptoms, such as anosmia and ageusia in patients infected with SARS-CoV-2.
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Affiliation(s)
- Martina Donadoni
- Center for Neurovirology & Gene Editing, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | - Rafal Kaminski
- Center for Neurovirology & Gene Editing, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | - Shuren Liao
- Center for Neurovirology & Gene Editing, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | | | | | | | - Ilker K Sariyer
- Center for Neurovirology & Gene Editing, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA.
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3
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Genovese F, Reisert J, Kefalov VJ. Sensory Transduction in Photoreceptors and Olfactory Sensory Neurons: Common Features and Distinct Characteristics. Front Cell Neurosci 2021; 15:761416. [PMID: 34690705 PMCID: PMC8531253 DOI: 10.3389/fncel.2021.761416] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/20/2021] [Indexed: 12/24/2022] Open
Abstract
The past decades have seen tremendous progress in our understanding of the function of photoreceptors and olfactory sensory neurons, uncovering the mechanisms that determine their properties and, ultimately, our ability to see and smell. This progress has been driven to a large degree by the powerful combination of physiological experimental tools and genetic manipulations, which has enabled us to identify the main molecular players in the transduction cascades of these sensory neurons, how their properties affect the detection and discrimination of stimuli, and how diseases affect our senses of vision and smell. This review summarizes some of the common and unique features of photoreceptors and olfactory sensory neurons that make these cells so exciting to study.
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Affiliation(s)
| | | | - Vladimir J Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA, United States.,Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
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4
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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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5
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Kalbe B, Schlimm M, Mohrhardt J, Scholz P, Jansen F, Hatt H, Osterloh S. Helional induces Ca2+ decrease and serotonin secretion of QGP-1 cells via a PKG-mediated pathway. J Mol Endocrinol 2016; 57:201-10. [PMID: 27553203 DOI: 10.1530/jme-16-0063] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 08/22/2016] [Indexed: 12/30/2022]
Abstract
The secretion, motility and transport by intestinal tissues are regulated among others by specialized neuroendocrine cells, the so-called enterochromaffin (EC) cells. These cells detect different luminal stimuli, such as mechanical stimuli, fatty acids, glucose and distinct chemosensory substances. The EC cells react to the changes in their environment through the release of transmitter molecules, most importantly serotonin, to mediate the corresponding physiological response. However, little is known about the molecular targets of the chemical stimuli delivered from consumed food, spices and cosmetics within EC cells. In this study, we evaluated the expression of the olfactory receptor (OR) 2J3 in the human pancreatic EC cell line QGP-1 at the mRNA and protein levels. Using ratiofluorometric Ca(2+) imaging experiments, we demonstrated that the OR2J3-specific agonist helional induces a transient dose-dependent decrease in the intracellular Ca(2+) levels. This Ca(2+) decrease is mediated by protein kinase G (PKG) on the basis that the specific pharmacological inhibition of PKG with Rp-8-pCPT-cGMPS abolished the helional-induced Ca(2+) response. Furthermore, stimulation of QGP-1 cells with helional caused a dose-dependent release of serotonin that was comparable with the release induced by the application of a direct PKG activator (8-bromo-cGMP). Taken together, our results demonstrate that luminal odorants can be detected by specific ORs in QGP-1 cells and thus cause the directed release of serotonin and a PKG-dependent decrease in intracellular Ca(2.)
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Affiliation(s)
- Benjamin Kalbe
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
| | - Marian Schlimm
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
| | - Julia Mohrhardt
- Department of ChemosensationInstitute for Biology II, RWTH Aachen University, Aachen, Germany
| | - Paul Scholz
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
| | - Fabian Jansen
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
| | - Hanns Hatt
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
| | - Sabrina Osterloh
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
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6
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Szebenyi SA, Ogura T, Sathyanesan A, AlMatrouk AK, Chang J, Lin W. Increases in intracellular calcium via activation of potentially multiple phospholipase C isozymes in mouse olfactory neurons. Front Cell Neurosci 2014; 8:336. [PMID: 25374507 PMCID: PMC4204526 DOI: 10.3389/fncel.2014.00336] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 10/01/2014] [Indexed: 11/13/2022] Open
Abstract
Phospholipase C (PLC) and internal Ca(2+) stores are involved in a variety of cellular functions. However, our understanding of PLC in mammalian olfactory sensory neurons (OSNs) is generally limited to its controversial role in odor transduction. Here we employed single-cell Ca(2+) imaging and molecular approaches to investigate PLC-mediated Ca(2+) responses and its isozyme gene transcript expression. We found that the pan-PLC activator m-3M3FBS (25 μM) induces intracellular Ca(2+) increases in vast majority of isolated mouse OSNs tested. Both the response amplitude and percent responding cells depend on m-3M3FBS concentrations. In contrast, the inactive analog o-3M3FBS fails to induce Ca(2+) responses. The m-3M3FBS-induced Ca(2+) increase is blocked by the PLC inhibitor U73122, while its inactive analog U73433 has no effect. Removal of extracellular Ca(2+) does not change significantly the m-3M3FBS-induced Ca(2+) response amplitude. Additionally, in the absence of external Ca(2+), we found that a subset of OSNs respond to an odorant mixture with small Ca(2+) increases, which are significantly suppressed by U73122. Furthermore, using reverse transcription polymerase chain reaction and real-time quantitative polymerase chain reaction, we found that multiple PLC isozyme gene transcripts are expressed in olfactory turbinate tissue in various levels. Using RNA in situ hybridization analysis, we further show expression of β4, γ1, γ2 gene transcripts in OSNs. Taken together, our results establish that PLC isozymes are potent enzymes for mobilizing intracellular Ca(2+) in mouse OSNs and provide molecular insight for PLC isozymes-mediated complex cell signaling and regulation in the peripheral olfactory epithelium.
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Affiliation(s)
- Steven A Szebenyi
- Department of Biological Sciences, University of Maryland Baltimore County Baltimore, MD, USA
| | - Tatsuya Ogura
- Department of Biological Sciences, University of Maryland Baltimore County Baltimore, MD, USA
| | - Aaron Sathyanesan
- Department of Biological Sciences, University of Maryland Baltimore County Baltimore, MD, USA
| | - Abdullah K AlMatrouk
- Department of Biological Sciences, University of Maryland Baltimore County Baltimore, MD, USA
| | - Justin Chang
- Department of Biological Sciences, University of Maryland Baltimore County Baltimore, MD, USA
| | - Weihong Lin
- Department of Biological Sciences, University of Maryland Baltimore County Baltimore, MD, USA
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Kamath V, Moberg PJ, Calkins ME, Borgmann-Winter K, Conroy CG, Gur RE, Kohler CG, Turetsky BI. An odor-specific threshold deficit implicates abnormal cAMP signaling in youths at clinical risk for psychosis. Schizophr Res 2012; 138:280-4. [PMID: 22537567 PMCID: PMC3372687 DOI: 10.1016/j.schres.2012.03.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 03/23/2012] [Accepted: 03/26/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND While olfactory deficits have been reported in schizophrenia and youths at-risk for psychosis, few studies have linked these deficits to current pathophysiological models of the illness. There is evidence that disrupted cyclic adenosine 3',5'-monophosphate (cAMP) signaling may contribute to schizophrenia pathology. As cAMP mediates olfactory signal transduction, the degree to which this disruption could manifest in olfactory impairment was ascertained. Odor-detection thresholds to two odorants that differ in the degree to which they activate intracellular cAMP were assessed in clinical risk and low-risk participants. METHOD Birhinal assessments of odor-detection threshold sensitivity to lyral and citralva were acquired in youths experiencing prodromal symptoms (n=17) and controls at low risk for developing psychosis (n=15). Citralva and lyral are odorants that differ in cAMP activation; citralva is a strong cAMP activator and lyral is a weak cAMP activator. RESULTS The overall group-by-odor interaction was statistically significant. At-risk youths showed significantly reduced odor detection thresholds for lyral, but showed intact detection thresholds for citralva. This odor-specific threshold deficit was uncorrelated with deficits in odor identification or discrimination, which were also present. ROC curve analysis revealed that olfactory performance correctly classified at-risk and low-risk youths with greater than 97% accuracy. CONCLUSIONS This study extends prior findings of an odor-specific hyposmia implicating cAMP-mediated signal transduction in schizophrenia and unaffected first-degree relatives to include youths at clinical risk for developing the disorder. These results suggest that dysregulation of cAMP signaling may be present during the psychosis prodrome.
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Affiliation(s)
- Vidyulata Kamath
- Neuropsychiatry Section, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
| | - Paul J. Moberg
- Neuropsychiatry Section, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA,Smell and Taste Center, Department of Otorhinolaryngology: Head & Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
| | - Monica E. Calkins
- Neuropsychiatry Section, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
| | - Karin Borgmann-Winter
- Neuropsychiatry Section, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA,Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Catherine G. Conroy
- Neuropsychiatry Section, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
| | - Raquel E. Gur
- Neuropsychiatry Section, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA,Department of Radiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
| | - Christian G. Kohler
- Neuropsychiatry Section, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
| | - Bruce I. Turetsky
- Neuropsychiatry Section, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA,Smell and Taste Center, Department of Otorhinolaryngology: Head & Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
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8
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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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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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10
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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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11
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Otsuguro KI, Gautam SH, Ito S, Habara Y, Saito T. Characterization of forskolin-induced Ca2+ signals in rat olfactory receptor neurons. J Pharmacol Sci 2005; 97:510-8. [PMID: 15821339 DOI: 10.1254/jphs.fp0040883] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Forskolin-induced Ca(2+) signals were examined in isolated rat olfactory receptor neurons (ORNs) using a Ca(2+) indicator, fura-2. In the soma of the ORNs, forskolin caused an increase in the intracellular Ca(2+) concentration ([Ca(2+)](i)) that was enhanced by a phosphodiesterase (PDE) 1 inhibitor, 8-methoxymethyl-3-isobutyl-1-methyl-xanthine, but not a PDE4 inhibitor, rolipram. Forskolin-induced Ca(2+) signals were abolished with the removal of extracellular Ca(2+) and un-affected by treatment with thapsigargin or caffeine plus ryanodine. Niflumic acid, a Ca(2+)-activated Cl(-) channel inhibitor, or nifedipine, an L-type Ca(2+) channel inhibitor, slowed the initial rate of the increase in [Ca(2+)](i) in response to forskolin. Nifedipine did not affect the increase in [Ca(2+)](i) that was slowed by niflumic acid. In Ca(2+) measurements with a confocal microscope and a calcium indicator, Fluo-4, the onset of the response to forskolin in the knob region occurred simultaneously or earlier, but not later, than that in the soma. It is suggested that the forskolin-induced Ca(2+) signals are due to Ca(2+) influx, but not the release of Ca(2+) from Ca(2+) stores, and that the initial rapid increase in [Ca(2+)](i) is associated with the activation of the voltage-dependent Ca(2+) channels in rat ORNs.
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Affiliation(s)
- Ken-ichi Otsuguro
- Laboratory of Pharmacology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
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12
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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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13
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Cadiou H, Molle G. Adenophostin A and imipramine are two activators of the olfactory inositol 1,4,5-trisphosphate-gated channel in fish olfatory cilia. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2003; 32:106-12. [PMID: 12734698 DOI: 10.1007/s00249-002-0271-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2002] [Accepted: 11/19/2002] [Indexed: 10/25/2022]
Abstract
Binding of an odorant to its receptor activates the cAMP-dependent pathway, and also leads to inositol 1,4,5-trisphosphate (InsP(3)) production. This induces opening of a plasma membrane channel in olfactory receptor cells (ORCs). We investigated single-channel properties of this channel in the presence of a phospholipase C (PLC) activator (imipramine) and of a potent activator of the InsP(3)/Ca(2+) release channel (adenophostin A) by reconstituting carp olfactory cilia into planar lipid bilayers. In the presence of 53 mM barium as a charge carrier, the addition of 50 microM imipramine induced a current of 1.53+/-0.05 pA at 0 mV. There were two different mean open times (6.0+/-0.6 ms and 49.6+/-6.4 ms). The I/ V curve displayed a slope conductance of 50+/-2 pS. Channel activity was transient and was blocked by neomycin (50 microM). These observations suggest that imipramine may activate the olfactory InsP(3)-gated channel through PLC. Using the same ionic conditions, the application of 0.5 microM adenophostin A triggered a current of 1.47+/-0.04 pA at 0 mV. The I/ V curve displayed a slope conductance of 60+/-2 pS. This channel showed only a single mean open time (15.0+/-0.3 ms) and was strongly inhibited by ruthenium red (30 microM) and heparin (10 microg/mL). These results indicate that adenophostin A and imipramine may act on the ciliary InsP(3)-gated channel and are potentially valuable pharmacological tools for studying olfactory transduction mechanisms.
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Affiliation(s)
- Hervé Cadiou
- UMR 6522 CNRS, IFRMP 23, Université de Rouen, 76821 Mont-Saint-Aignan, France
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Lane AP, Gomez G, Dankulich T, Wang H, Bolger WE, Rawson NE. The superior turbinate as a source of functional human olfactory receptor neurons. Laryngoscope 2002; 112:1183-9. [PMID: 12169895 DOI: 10.1097/00005537-200207000-00007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES The function of human olfactory receptor neurons (ORNs) remains incompletely understood, in part because of the difficulty of obtaining viable olfactory tissue for study. During endoscopic sphenoidotomy, a portion of the superior turbinate is often removed to achieve wide and safe access to the sphenoid sinus. The purpose of this study was to determine whether functional olfactory mucosa could be obtained from such superior turbinate tissue. STUDY DESIGN/METHODS Superior turbinate tissue was resected from 4 patients undergoing transnasal endoscopic approaches to the sphenoid sinus. The gross appearance of the turbinate mucosa was normal at the time of surgery. The specimens were placed directly into cold cell culture media and transferred to the laboratory. A portion of the mucosa was fixed and embedded for histology and immunohistochemistry. The remaining tissue was enzymatically dissociated, and the resulting cell suspension was either prepared for immediate calcium imaging or placed into cell culture. Cultured ORNs underwent calcium imaging after several weeks to assess their ability to respond to odorants. RESULTS Histologic analysis of superior turbinate tissue revealed the presence of patchy olfactory neuroepithelium staining positive for olfactory marker protein. Acutely dissociated ORNs were capable of generating calcium responses to odorant mixtures. ORNs could be maintained in mixed culture and retained their ability to respond to odorants. CONCLUSIONS Superior turbinate tissue removed during endoscopic sphenoidotomy can provide a valuable source of human olfactory neuroepithelium for functional or histologic study. Superior turbinate tissue yields stem cells and immature neurons capable of differentiating into ORNs that retain many of their functional characteristics even after growth in culture.
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Affiliation(s)
- Andrew P Lane
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, U.S.A.
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Spehr M, Wetzel CH, Hatt H, Ache BW. 3-phosphoinositides modulate cyclic nucleotide signaling in olfactory receptor neurons. Neuron 2002; 33:731-9. [PMID: 11879650 DOI: 10.1016/s0896-6273(02)00610-4] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Phosphatidylinositol 3-kinase (PI3K)-dependent phosphoinositide signaling has been implicated in diverse cellular systems coupled to receptors for many different ligands, but the extent to which it functions in sensory transduction is yet to be determined. We now report that blocking PI3K activity increases odorant-evoked, cyclic nucleotide-dependent elevation of [Ca(2+)](i) in acutely dissociated rat olfactory receptor neurons and does so in an odorant-specific manner. These findings imply that 3-phosphoinositide signaling acts in vertebrate olfactory transduction to inhibit cyclic nucleotide-dependent excitation of the cells and that the interaction of the two signaling pathways is important in odorant coding, indicating that 3-phosphoinositide signaling can play a role in sensory transduction.
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Affiliation(s)
- Marc Spehr
- Department of Cell Physiology, Ruhr University Bochum, Bochum, Germany
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Abstract
Functional imaging methods permit analysis of neuronal systems in which activity is broadly distributed in time and space. In the olfactory system the dimensions that describe odorant stimuli in "odorant space" are still poorly defined. One way of trying to characterize the attributes of this space is to examine the ways in which its dimensions are encoded by the neurons and circuits making up the system and to compare these responses with physical-chemical attributes of the stimuli and with the output behavior of the animal. For documenting distributed events as they occur, imaging methods are among the few tools available. We are still in the early stages of this analysis; however, a number of recent studies have contributed new information to our understanding of the odorant coding problem. This paper describes imaging results in the context of other data that have contributed to our understanding of how odors are encoded by the peripheral olfactory pathway.
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Affiliation(s)
- J S Kauer
- Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, Massachusetts 02111, 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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