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Cain MD, Klein NR, Jiang X, Salimi H, Wu Q, Miller MJ, Klimstra WB, Klein RS. Post-exposure intranasal IFNα suppresses replication and neuroinvasion of Venezuelan Equine Encephalitis virus within olfactory sensory neurons. J Neuroinflammation 2024; 21:24. [PMID: 38233868 PMCID: PMC10792865 DOI: 10.1186/s12974-023-02960-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 11/14/2023] [Indexed: 01/19/2024] Open
Abstract
BACKGROUND Venezuelan Equine Encephalitis virus (VEEV) may enter the central nervous system (CNS) within olfactory sensory neurons (OSN) that originate in the nasal cavity after intranasal exposure. While it is known that VEEV has evolved several mechanisms to inhibit type I interferon (IFN) signaling within infected cells, whether this inhibits virologic control during neuroinvasion along OSN has not been studied. METHODS We utilized an established murine model of intranasal infection with VEEV and a repository of scRNAseq data from IFN-treated OSN to assess the cellular targets and IFN signaling responses after VEEV exposure. RESULTS We found that immature OSN, which express higher levels of the VEEV receptor LDLRAD3 than mature OSN, are the first cells infected by VEEV. Despite rapid VEEV neuroinvasion after intranasal exposure, olfactory neuroepithelium (ONE) and olfactory bulb (OB) IFN responses, as assessed by evaluation of expression of interferon signaling genes (ISG), are delayed for up to 48 h during VEEV neuroinvasion, representing a potential therapeutic window. Indeed, a single intranasal dose of recombinant IFNα triggers early ISG expression in both the nasal cavity and OB. When administered at the time of or early after infection, IFNα treatment delayed onset of sequelae associated with encephalitis and extended survival by several days. VEEV replication after IFN treatment was also transiently suppressed in the ONE, which inhibited subsequent invasion into the CNS. CONCLUSIONS Our results demonstrate a critical and promising first evaluation of intranasal IFNα for the treatment of human encephalitic alphavirus exposures.
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Affiliation(s)
- Matthew D Cain
- Center for Neuroimmunology & Neuroinfectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Departments of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - N Rubin Klein
- Departments of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Xiaoping Jiang
- Center for Neuroimmunology & Neuroinfectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Departments of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Hamid Salimi
- Center for Neuroimmunology & Neuroinfectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Departments of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Qingping Wu
- Center for Neuroimmunology & Neuroinfectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Departments of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Mark J Miller
- Departments of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - William B Klimstra
- Department of Immunology and Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Robyn S Klein
- Center for Neuroimmunology & Neuroinfectious Diseases, Washington University School of Medicine, St. Louis, MO, USA.
- Departments of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
- Departments of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA.
- Departments of Neurosciences, Washington University School of Medicine, St. Louis, MO, USA.
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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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Liu ZY, Vaira LA, Boscolo-Rizzo P, Walker A, Hopkins C. Post-viral olfactory loss and parosmia. BMJ MEDICINE 2023; 2:e000382. [PMID: 37841969 PMCID: PMC10568123 DOI: 10.1136/bmjmed-2022-000382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 05/26/2023] [Indexed: 10/17/2023]
Abstract
The emergence of SARS-CoV-2 has brought olfactory dysfunction to the forefront of public awareness, because up to half of infected individuals could develop olfactory dysfunction. Loss of smell-which can be partial or total-in itself is debilitating, but the distortion of sense of smell (parosmia) that can occur as a consequence of a viral upper respiratory tract infection (either alongside a reduction in sense of smell or as a solo symptom) can be very distressing for patients. Incidence of olfactory loss after SARS-CoV-2 infection has been estimated by meta-analysis to be around 50%, with more than one in three who will subsequently report parosmia. While early loss of sense of smell is thought to be due to infection of the supporting cells of the olfactory epithelium, the underlying mechanisms of persistant loss and parosmia remain less clear. Depletion of olfactory sensory neurones, chronic inflammatory infiltrates, and downregulation of receptor expression are thought to contribute. There are few effective therapeutic options, so support and olfactory training are essential. Further research is required before strong recommendations can be made to support treatment with steroids, supplements, or interventions applied topically or injected into the olfactory epithelium in terms of improving recovery of quantitative olfactory function. It is not yet known whether these treatments will also achieve comparable improvements in parosmia. This article aims to contextualise parosmia in the setting of post-viral olfactory dysfunction, explore some of the putative molecular mechanisms, and review some of the treatment options available.
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Affiliation(s)
- Zhen Yu Liu
- Department of ENT Surgery, Royal Brisbane and Women's Hospital, Herston, QLD, Australia
| | - Luigi Angelo Vaira
- Department of Medicine, Surgery and Pharmacy, University of Sassari, Sassari, Sardegna, Italy
| | - Paolo Boscolo-Rizzo
- Department of Medical, Surgical, and Health Sciences, Section of Otolaryngology, University of Trieste, Trieste, Italy
| | - Abigail Walker
- Department of ENT, Royal Brisbane and Women's Hospital, Herston, QLD, Australia
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4
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Gerhardt MJ, Petersen-Jones SM, Michalakis S. CNG channel-related retinitis pigmentosa. Vision Res 2023; 208:108232. [PMID: 37054604 PMCID: PMC10373105 DOI: 10.1016/j.visres.2023.108232] [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: 02/13/2023] [Revised: 03/27/2023] [Accepted: 03/27/2023] [Indexed: 04/15/2023]
Abstract
The genes CNGA1 and CNGB1 encode the alpha and beta subunits of the rod CNG channel, a ligand-gated cation channel whose activity is controlled by cyclic guanosine monophosphate (cGMP). Autosomal inherited mutations in either of the genes lead to a progressive rod-cone retinopathy known as retinitis pigmentosa (RP). The rod CNG channel is expressed in the plasma membrane of the outer segment and functions as a molecular switch that converts light-mediated changes in cGMP into a voltage and Ca2+ signal. Here, we will first review the molecular properties and physiological role of the rod CNG channel and then discuss the characteristics of CNG-related RP. Finally, we will summarize recent activities in the field of gene therapy aimed at developing therapies for CNG-related RP.
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Affiliation(s)
- Maximilian J Gerhardt
- Department of Ophthalmology, University Hospital, LMU Munich, Mathildenstraße 8, 80336 München, Germany
| | - Simon M Petersen-Jones
- College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, United States
| | - Stylianos Michalakis
- Department of Ophthalmology, University Hospital, LMU Munich, Mathildenstraße 8, 80336 München, Germany.
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Cain MD, Klein NR, Jiang X, Klein RS. Post-exposure intranasal IFNα suppresses replication and neuroinvasion of Venezuelan Equine Encephalitis virus within olfactory sensory neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.30.547169. [PMID: 37425867 PMCID: PMC10327097 DOI: 10.1101/2023.06.30.547169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Venezuelan Equine Encephalitis virus (VEEV) may enter the central nervous system (CNS) within olfactory sensory neurons (OSN) that originate in the nasal cavity after intranasal exposure. While it is known that VEEV has evolved several mechanisms to inhibit type I interferon (IFN) signaling within infected cells, whether this inhibits virologic control during neuroinvasion along OSN has not been studied. Here, we utilized an established murine model of intranasal infection with VEEV to assess the cellular targets and IFN signaling responses after VEEV exposure. We found that immature OSN, which express higher levels of the VEEV receptor LDLRAD3 than mature OSN, are the first cells infected by VEEV. Despite rapid VEEV neuroinvasion after intranasal exposure, olfactory neuroepithelium (ONE) and olfactory bulb (OB) IFN responses, as assessed by evaluation of expression of interferon signaling genes (ISG), are delayed for up to 48 hours during VEEV neuroinvasion, representing a potential therapeutic window. Indeed, a single intranasal dose of recombinant IFNα triggers early ISG expression in both the nasal cavity and OB. When administered at the time of or early after infection, IFNα treatment delayed onset of sequelae associated with encephalitis and extended survival by several days. VEEV replication after IFN treatment was also transiently suppressed in the ONE, which inhibited subsequent invasion into the CNS. Our results demonstrate a critical and promising first evaluation of intranasal IFNα for the treatment of human encephalitic alphavirus exposures.
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Affiliation(s)
- Matthew D. Cain
- Center for Neuroimmunology & Neuroinfectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - N. Rubin Klein
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Xiaoping Jiang
- Center for Neuroimmunology & Neuroinfectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Robyn S. Klein
- Center for Neuroimmunology & Neuroinfectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
- Department of Neurosciences, Washington University School of Medicine, St. Louis, MO, USA
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6
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Takeuchi H, Kurahashi T. Segregation of Ca2+ signaling in olfactory signal transduction. J Gen Physiol 2023; 155:213865. [PMID: 36787110 PMCID: PMC9960254 DOI: 10.1085/jgp.202213165] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 11/04/2022] [Accepted: 01/13/2023] [Indexed: 02/15/2023] Open
Abstract
Olfactory signal transduction is conducted through a cAMP-mediated second messenger cascade. The cytoplasmic Ca2+ concentration increases through the opening of CNG channels, a phenomenon that underlies two major functions, namely, signal boosting and olfactory adaptation. Signal boosting is achieved by an additional opening of the Ca2+-activated Cl- channel whereas adaptation is regulated by Ca2+ feedback to the CNG channel. Thus, the influx of Ca2+ and the resultant increase in cytoplasmic Ca2+ levels play seemingly opposing effects: increasing the current while reducing the current through adaptation. The two functions could be interpreted as compensating for each other. However, in real cells, both functions should be segregated. Ca2+ dynamics in olfactory cilia need to be directly measured, but technical difficulties accompanying the thin structure of olfactory cilia have prevented systematic analyses. In this study, using a combination of electrophysiology, local photolysis of caged cAMP, and Ca2+ imaging, we found that free Ca2+ in the local ciliary cytoplasm decreased along with a reduction in the current containing Ca2+-activated Cl- components returning to the basal level, whereas Ca2+-dependent adaptation persisted for a longer period. The activity of Cl- channels is highly likely to be regulated by the free Ca2+ that is present only immediately after the influx through the CNG channel, and an exclusive interaction between Ca2+ and Ca2+-binding proteins that mediate the adaptation may modulate the adaptation lifetime.
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Affiliation(s)
- Hiroko Takeuchi
- Department of Biophysical Dynamics, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
- Correspondence to Hiroko Takeuchi:
| | - Takashi Kurahashi
- Department of Biophysical Dynamics, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
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7
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Short B. Sniffing out Ca2+ signaling in olfactory cilia. J Gen Physiol 2023; 155:e202313378. [PMID: 36946993 PMCID: PMC10072153 DOI: 10.1085/jgp.202313378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023] Open
Abstract
JGP study (Takeuchi and Kurahashi. 2023. J. Gen. Physiol.https://doi.org/10.1085/jgp.202213165) reveals that segregation of signals within sensory cilia allows Ca2+ to play opposing roles in olfactory signal transduction.
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8
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Ferrulli A, Senesi P, Terruzzi I, Luzi L. Eating Habits and Body Weight Changes Induced by Variation in Smell and Taste in Patients with Previous SARS-CoV-2 Infection. Nutrients 2022; 14:nu14235068. [PMID: 36501098 PMCID: PMC9738767 DOI: 10.3390/nu14235068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/11/2022] [Accepted: 11/15/2022] [Indexed: 11/30/2022] Open
Abstract
Olfactory and gustatory dysfunction are recognized as common symptoms in patients with COVID-19, with a prevalence ranging, respectively, between 41-61% and 38.2-49%. This review focused on relating the variations in dietary habits with the reduction/loss of smell and/or taste in patients who contracted the COVID-19 infection. Primarily, we reviewed the main pathological mechanisms involved in COVID 19-induced anosmia/dysosmia and ageusia/dysgeusia. Then, we explored and summarized the behavioural changes in food intake and body weight during the COVID-19 pandemic in relation to sensory impairment and the underlying mechanisms. Most studies on this topic argue that the altered chemosensory perception (taste and smell) mainly induces reduced appetite, leading to a faster fullness sensation during the consumption of a meal and, therefore, to a decrease in body weight. On the other hand, a reduced perception of the food's sensory properties may trigger compensatory responses that lead some individuals to increase food intake with a different effect on body weight. Regarding body weight, most studies evaluated malnutrition in patients hospitalized for COVID-19; more studies are warranted to investigate nutritional status specifically in non-hospitalized patients with olfactory and gustatory dysfunctions caused by COVID-19 infection.
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Affiliation(s)
- Anna Ferrulli
- Department of Endocrinology, Nutrition and Metabolic Diseases, IRCCS MultiMedica, 20138 Milan, Italy
- Department of Biomedical Sciences for Health, University of Milan, 20133 Milan, Italy
- Correspondence: or ; Tel.: +39-02-8599-4572
| | - Pamela Senesi
- Department of Endocrinology, Nutrition and Metabolic Diseases, IRCCS MultiMedica, 20138 Milan, Italy
- Department of Biomedical Sciences for Health, University of Milan, 20133 Milan, Italy
| | - Ileana Terruzzi
- Department of Endocrinology, Nutrition and Metabolic Diseases, IRCCS MultiMedica, 20138 Milan, Italy
- Department of Biomedical Sciences for Health, University of Milan, 20133 Milan, Italy
| | - Livio Luzi
- Department of Endocrinology, Nutrition and Metabolic Diseases, IRCCS MultiMedica, 20138 Milan, Italy
- Department of Biomedical Sciences for Health, University of Milan, 20133 Milan, Italy
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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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Manzini I, Schild D, Di Natale C. Principles of odor coding in vertebrates and artificial chemosensory systems. Physiol Rev 2021; 102:61-154. [PMID: 34254835 DOI: 10.1152/physrev.00036.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The biological olfactory system is the sensory system responsible for the detection of the chemical composition of the environment. Several attempts to mimic biological olfactory systems have led to various artificial olfactory systems using different technical approaches. Here we provide a parallel description of biological olfactory systems and their technical counterparts. We start with a presentation of the input to the systems, the stimuli, and treat the interface between the external world and the environment where receptor neurons or artificial chemosensors reside. We then delineate the functions of receptor neurons and chemosensors as well as their overall I-O relationships. Up to this point, our account of the systems goes along similar lines. The next processing steps differ considerably: while in biology the processing step following the receptor neurons is the "integration" and "processing" of receptor neuron outputs in the olfactory bulb, this step has various realizations in electronic noses. For a long period of time, the signal processing stages beyond the olfactory bulb, i.e., the higher olfactory centers were little studied. Only recently there has been a marked growth of studies tackling the information processing in these centers. In electronic noses, a third stage of processing has virtually never been considered. In this review, we provide an up-to-date overview of the current knowledge of both fields and, for the first time, attempt to tie them together. We hope it will be a breeding ground for better information, communication, and data exchange between very related but so far little connected fields.
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Affiliation(s)
- Ivan Manzini
- Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Gießen, Gießen, Germany
| | - Detlev Schild
- Institute of Neurophysiology and Cellular Biophysics, University Medical Center, University of Göttingen, Göttingen, Germany
| | - Corrado Di Natale
- Department of Electronic Engineering, University of Rome Tor Vergata, Rome, Italy
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Abbas F, Vinberg F. Transduction and Adaptation Mechanisms in the Cilium or Microvilli of Photoreceptors and Olfactory Receptors From Insects to Humans. Front Cell Neurosci 2021; 15:662453. [PMID: 33867944 PMCID: PMC8046925 DOI: 10.3389/fncel.2021.662453] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 03/02/2021] [Indexed: 12/11/2022] Open
Abstract
Sensing changes in the environment is crucial for survival. Animals from invertebrates to vertebrates use both visual and olfactory stimuli to direct survival behaviors including identification of food sources, finding mates, and predator avoidance. In primary sensory neurons there are signal transduction mechanisms that convert chemical or light signals into an electrical response through ligand binding or photoactivation of a receptor, that can be propagated to the olfactory and visual centers of the brain to create a perception of the odor and visual landscapes surrounding us. The fundamental principles of olfactory and phototransduction pathways within vertebrates are somewhat analogous. Signal transduction in both systems takes place in the ciliary sub-compartments of the sensory cells and relies upon the activation of G protein-coupled receptors (GPCRs) to close cyclic nucleotide-gated (CNG) cation channels in photoreceptors to produce a hyperpolarization of the cell, or in olfactory sensory neurons open CNG channels to produce a depolarization. However, while invertebrate phototransduction also involves GPCRs, invertebrate photoreceptors can be either ciliary and/or microvillar with hyperpolarizing and depolarizing responses to light, respectively. Moreover, olfactory transduction in invertebrates may be a mixture of metabotropic G protein and ionotropic signaling pathways. This review will highlight differences of the visual and olfactory transduction mechanisms between vertebrates and invertebrates, focusing on the implications to the gain of the transduction processes, and how they are modulated to allow detection of small changes in odor concentration and light intensity over a wide range of background stimulus levels.
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Affiliation(s)
- Fatima Abbas
- Vinberg Lab, Department of Ophthalmology and Visual Science, John A. Moran Center, University of Utah, Salt Lake City, UT, United States
| | - Frans Vinberg
- Vinberg Lab, Department of Ophthalmology and Visual Science, John A. Moran Center, University of Utah, Salt Lake City, UT, United States
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12
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Affiliation(s)
- Silke Sachse
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, 07745, Jena, Germany.
| | - Ivan Manzini
- Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, Giessen, Germany.
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