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Bhatia V, de Jesus VC, Shaik FA, Jaggupilli A, Singh N, Chelikani P, Atukorallaya D. Extraoral expression and characterization of bitter taste receptors in
Astyanax mexicanus
(Mexican Tetra Fish). FASEB Bioadv 2022; 4:574-584. [PMID: 36089978 PMCID: PMC9447421 DOI: 10.1096/fba.2022-00032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/29/2022] [Accepted: 05/04/2022] [Indexed: 11/11/2022] Open
Affiliation(s)
- Vikram Bhatia
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
- Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg MB R3E3P4 Canada
| | - Vivianne Cruz de Jesus
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
- Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg MB R3E3P4 Canada
| | - Feroz Ahmed Shaik
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
| | - Appalaraju Jaggupilli
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
| | - Nisha Singh
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
| | - Prashen Chelikani
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
- Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg MB R3E3P4 Canada
| | - Devi Atukorallaya
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
- Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg MB R3E3P4 Canada
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2
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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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3
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A comprehensive structural, lectin and immunohistochemical characterization of the zebrafish olfactory system. Sci Rep 2021; 11:8865. [PMID: 33893372 PMCID: PMC8065131 DOI: 10.1038/s41598-021-88317-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 04/12/2021] [Indexed: 12/30/2022] Open
Abstract
Fish chemosensory olfactory receptors allow them to detect a wide range of water-soluble chemicals, that mediate fundamental behaviours. Zebrafish possess a well-developed sense of smell which governs reproduction, appetite, and fear responses. The spatial organization of functional properties within the olfactory epithelium and bulb are comparable to those of mammals, making this species suitable for studies of olfactory differentiation and regeneration and neuronal representation of olfactory information. The advent of genomic techniques has been decisive for the discovery of specific olfactory cell types and the identification of cell populations expressing vomeronasal receptors. These advances have marched ahead of morphological and neurochemical studies. This study aims to fill the existing gap in specific histological, lectin-histochemical and immunohistochemical studies on the olfactory rosette and the olfactory bulb of the zebrafish. Tissue dissection and microdissection techniques were employed, followed by histological staining techniques, lectin-histochemical labelling (UEA, LEA, BSI-B4) and immunohistochemistry using antibodies against G proteins subunits αo and αi2, growth-associated protein-43, calbindin, calretinin, glial-fibrillary-acidic-protein and luteinizing-hormone-releasing-hormone. The results obtained enrich the available information on the neurochemical patterns of the zebrafish olfactory system, pointing to a greater complexity than the one currently considered, especially when taking into account the peculiarities of the nonsensory epithelium.
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4
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Diving into the streams and waves of constitutive and regenerative olfactory neurogenesis: insights from zebrafish. Cell Tissue Res 2020; 383:227-253. [PMID: 33245413 DOI: 10.1007/s00441-020-03334-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/02/2020] [Indexed: 02/06/2023]
Abstract
The olfactory system is renowned for its functional and structural plasticity, with both peripheral and central structures displaying persistent neurogenesis throughout life and exhibiting remarkable capacity for regenerative neurogenesis after damage. In general, fish are known for their extensive neurogenic ability, and the zebrafish in particular presents an attractive model to study plasticity and adult neurogenesis in the olfactory system because of its conserved structure, relative simplicity, rapid cell turnover, and preponderance of neurogenic niches. In this review, we present an overview of the anatomy of zebrafish olfactory structures, with a focus on the neurogenic niches in the olfactory epithelium, olfactory bulb, and ventral telencephalon. Constitutive and regenerative neurogenesis in both the peripheral olfactory organ and central olfactory bulb of zebrafish is reviewed in detail, and a summary of current knowledge about the cellular origin and molecular signals involved in regulating these processes is presented. While some features of physiologic and injury-induced neurogenic responses are similar, there are differences that indicate that regeneration is not simply a reiteration of the constitutive proliferation process. We provide comparisons to mammalian neurogenesis that reveal similarities and differences between species. Finally, we present a number of open questions that remain to be answered.
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5
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Tran S, Chow H, Tsang B, Facciol A, Gandhi P, Desai P, Gerlai R. Zebrafish Are Able to Detect Ethanol in Their Environment. Zebrafish 2017; 14:126-132. [DOI: 10.1089/zeb.2016.1372] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Steven Tran
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Hayden Chow
- Department of Physiology and Pharmacology, University of Western Ontario, London, Canada
| | - Benjamin Tsang
- Department of Psychology, University of Toronto Mississauga, Mississauga, Canada
| | - Amanda Facciol
- Department of Psychology, University of Toronto Mississauga, Mississauga, Canada
| | - Prabhlene Gandhi
- Department of Psychology, University of Toronto Mississauga, Mississauga, Canada
| | - Priyanka Desai
- Department of Psychology, University of Toronto Mississauga, Mississauga, Canada
| | - Robert Gerlai
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
- Department of Psychology, University of Toronto Mississauga, Mississauga, Canada
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6
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Wanner AA, Genoud C, Friedrich RW. 3-dimensional electron microscopic imaging of the zebrafish olfactory bulb and dense reconstruction of neurons. Sci Data 2016; 3:160100. [PMID: 27824337 PMCID: PMC5100684 DOI: 10.1038/sdata.2016.100] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 09/22/2016] [Indexed: 01/27/2023] Open
Abstract
Large-scale reconstructions of neuronal populations are critical for structural analyses of neuronal cell types and circuits. Dense reconstructions of neurons from image data require ultrastructural resolution throughout large volumes, which can be achieved by automated volumetric electron microscopy (EM) techniques. We used serial block face scanning EM (SBEM) and conductive sample embedding to acquire an image stack from an olfactory bulb (OB) of a zebrafish larva at a voxel resolution of 9.25×9.25×25 nm3. Skeletons of 1,022 neurons, 98% of all neurons in the OB, were reconstructed by manual tracing and efficient error correction procedures. An ergonomic software package, PyKNOSSOS, was created in Python for data browsing, neuron tracing, synapse annotation, and visualization. The reconstructions allow for detailed analyses of morphology, projections and subcellular features of different neuron types. The high density of reconstructions enables geometrical and topological analyses of the OB circuitry. Image data can be accessed and viewed through the neurodata web services (http://www.neurodata.io). Raw data and reconstructions can be visualized in PyKNOSSOS.
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Affiliation(s)
- Adrian A. Wanner
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- University of Basel, 4003 Basel, Switzerland
| | - Christel Genoud
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Rainer W. Friedrich
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- University of Basel, 4003 Basel, Switzerland
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7
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Yáñez J, Souto Y, Piñeiro L, Folgueira M, Anadón R. Gustatory and general visceral centers and their connections in the brain of adult zebrafish: a carbocyanine dye tract-tracing study. J Comp Neurol 2016; 525:333-362. [PMID: 27343143 DOI: 10.1002/cne.24068] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 06/21/2016] [Accepted: 06/22/2016] [Indexed: 02/04/2023]
Abstract
The central connections of the gustatory/general visceral system of the adult zebrafish (Danio rerio) were examined by means of carbocyanine dye tracing. Main primary gustatory centers (facial and vagal lobes) received sensory projections from the facial and vagal nerves, respectively. The vagal nerve also projects to the commissural nucleus of Cajal, a general visceral sensory center. These primary centers mainly project on a prominent secondary gustatory and general visceral nucleus (SGN/V) located in the isthmic region. Secondary projections on the SGN/V were topographically organized, those of the facial lobe mainly ending medially to those of the vagal lobe, and those from the commissural nucleus ventrolaterally. Descending facial lobe projections to the medial funicular nucleus were also noted. Ascending fibers originating from the SGN/V mainly projected to the posterior thalamic nucleus and the lateral hypothalamus (lateral torus, lateral recess nucleus, hypothalamic inferior lobe diffuse nucleus) and an intermediate cell- and fiber-rich region termed here the tertiary gustatory nucleus proper, but not to a nucleus formerly considered as the zebrafish tertiary gustatory nucleus. The posterior thalamic nucleus, tertiary gustatory nucleus proper, and nucleus of the lateral recess gave rise to descending projections to the SGN/V and the vagal lobe. The connectivity between diencephalic gustatory centers and the telencephalon was also investigated. The present results showed that the gustatory connections of the adult zebrafish are rather similar to those reported in other cyprinids, excepting the tertiary gustatory nucleus. Similarities between the gustatory systems of zebrafish and other fishes are also discussed. J. Comp. Neurol. 525:333-362, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Julián Yáñez
- Department of Cell and Molecular Biology, Faculty of Sciences, University of A Coruña, A Coruña, Spain.,Neurover Group, Centro de Investigaciones Científicas Avanzadas (CICA), University of A Coruña, A Coruña, Spain
| | - Yara Souto
- Department of Cell and Molecular Biology, Faculty of Sciences, University of A Coruña, A Coruña, Spain
| | - Laura Piñeiro
- Department of Cell and Molecular Biology, Faculty of Sciences, University of A Coruña, A Coruña, Spain
| | - Mónica Folgueira
- Department of Cell and Molecular Biology, Faculty of Sciences, University of A Coruña, A Coruña, Spain.,Neurover Group, Centro de Investigaciones Científicas Avanzadas (CICA), University of A Coruña, A Coruña, Spain
| | - Ramón Anadón
- Department of Cell Biology and Ecology, Faculty of Biology, University of Santiago de Compostela, Santiago de Compostela, Spain
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8
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Abstract
Among teleosts, cichlids are a great model for studies of evolution, behavior, diversity and speciation. Studies of cichlid sensory systems have revealed diverse sensory capabilities that vary among species. Hence, sensory systems are important for understanding cichlid behavior from proximate and ultimate points of view. Cichlids primarily rely on five sensory channels: hearing, mechanosensation, taste, vision, and olfaction, to receive information from the environment and respond accordingly. Within these sensory channels, cichlid species exhibit different adaptations to their surrounding environment, which differ in abiotic and biotic stimuli. Research on cichlid sensory capabilities and behaviors incorporates integrative approaches and relies on diverse scientific disciplines from physics to chemistry to neurobiology to understand the evolution of the cichlid sensory systems.
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Affiliation(s)
| | - Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD 20742, USA
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9
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Acid-sensing ion channel 2 (ASIC2) is selectively localized in the cilia of the non-sensory olfactory epithelium of adult zebrafish. Histochem Cell Biol 2014; 143:59-68. [PMID: 25161120 DOI: 10.1007/s00418-014-1264-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2014] [Indexed: 02/07/2023]
Abstract
Ionic channels play key roles in the sensory cells, such as transducing specific stimuli into electrical signals. The acid-sensing ion channel (ASIC) family is voltage-insensitive, amiloride-sensitive, proton-gated cation channels involved in several sensory functions. ASIC2, in particular, has a dual function as mechano- and chemo-sensor. In this study, we explored the possible role of zebrafish ASIC2 in olfaction. RT-PCR, Western blot, chromogenic in situ hybridization and immunohistochemistry, as well as ultrastructural analysis, were performed on the olfactory rosette of adult zebrafish. ASIC2 mRNA and protein were detected in homogenates of olfactory rosettes. Specific ASIC2 hybridization was observed in the luminal pole of the non-sensory epithelium, especially in the cilia basal bodies, and immunoreactivity for ASIC2 was restricted to the cilia of the non-sensory cells where it was co-localized with the cilia marker tubulin. ASIC2 expression was always absent in the olfactory cells. These findings demonstrate for the first time the expression of ASIC2 in the olfactory epithelium of adult zebrafish and suggest that it is not involved in olfaction. Since the cilium sense and transduce mechanical and chemical stimuli, ASIC2 expression in this location might be related to detection of aquatic environment pH variations or to detection of water movement through the nasal cavity.
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10
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Olfactory projectome in the zebrafish forebrain revealed by genetic single-neuron labelling. Nat Commun 2014; 5:3639. [DOI: 10.1038/ncomms4639] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 03/12/2014] [Indexed: 11/08/2022] Open
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11
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Latorre R, Mazzoni M, De Giorgio R, Vallorani C, Bonaldo A, Gatta PP, Corinaldesi R, Ruggeri E, Bernardini C, Chiocchetti R, Sternini C, Clavenzani P. Enteroendocrine profile of α-transducin immunoreactive cells in the gastrointestinal tract of the European sea bass (Dicentrarchus labrax). FISH PHYSIOLOGY AND BIOCHEMISTRY 2013; 39:1555-1565. [PMID: 23748963 PMCID: PMC3825768 DOI: 10.1007/s10695-013-9808-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Accepted: 05/17/2013] [Indexed: 06/02/2023]
Abstract
In vertebrates, chemosensitivity of nutrients occurs through the activation of taste receptors coupled with G-protein subunits, including α-transducin (G(αtran)) and α-gustducin (G(αgust)). This study was aimed at characterising the cells expressing G(αtran) immunoreactivity throughout the mucosa of the sea bass gastrointestinal tract. G(αtran) immunoreactive cells were mainly found in the stomach, and a lower number of immunopositive cells were detected in the intestine. Some G(αtran) immunoreactive cells in the stomach contained G(αgust) immunoreactivity. Gastric G(αtran) immunoreactive cells co-expressed ghrelin, obestatin and 5-hydroxytryptamine immunoreactivity. In contrast, G(αtran) immunopositive cells did not contain somatostatin, gastrin/cholecystokinin, glucagon-like peptide-1, substance P or calcitonin gene-related peptide immunoreactivity in any investigated segments of the sea bass gastrointestinal tract. Specificity of G(αtran) and G(αgust) antisera was determined by Western blot analysis, which identified two bands at the theoretical molecular weight of ~45 and ~40 kDa, respectively, in sea bass gut tissue as well as in positive tissue, and by immunoblocking with the respective peptide, which prevented immunostaining. The results of the present study provide a molecular and morphological basis for a role of taste-related molecules in chemosensing in the sea bass gastrointestinal tract.
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Affiliation(s)
- Rocco Latorre
- Department of Veterinary Medical Science, University of Bologna,
Italy, via Tolara di Sopra, 50, 40064 - Ozzano dell’Emilia, Bologna,
Italy
| | - Maurizio Mazzoni
- Department of Veterinary Medical Science, University of Bologna,
Italy, via Tolara di Sopra, 50, 40064 - Ozzano dell’Emilia, Bologna,
Italy
| | - Roberto De Giorgio
- Department of Medical and Surgical Sciences, University of Bologna,
Italy, St. Orsola-Malpighi Hospital, via Massarenti, 40138 - Bologna,
Italy
| | - Claudia Vallorani
- Department of Veterinary Medical Science, University of Bologna,
Italy, via Tolara di Sopra, 50, 40064 - Ozzano dell’Emilia, Bologna,
Italy
| | - Alessio Bonaldo
- Department of Veterinary Medical Science, University of Bologna,
Italy, via Tolara di Sopra, 50, 40064 - Ozzano dell’Emilia, Bologna,
Italy
| | - Pier Paolo Gatta
- Department of Veterinary Medical Science, University of Bologna,
Italy, via Tolara di Sopra, 50, 40064 - Ozzano dell’Emilia, Bologna,
Italy
| | - Roberto Corinaldesi
- Department of Medical and Surgical Sciences, University of Bologna,
Italy, St. Orsola-Malpighi Hospital, via Massarenti, 40138 - Bologna,
Italy
| | - Eugenio Ruggeri
- Department of Medical and Surgical Sciences, University of Bologna,
Italy, St. Orsola-Malpighi Hospital, via Massarenti, 40138 - Bologna,
Italy
| | - Chiara Bernardini
- Department of Veterinary Medical Science, University of Bologna,
Italy, via Tolara di Sopra, 50, 40064 - Ozzano dell’Emilia, Bologna,
Italy
| | - Roberto Chiocchetti
- Department of Veterinary Medical Science, University of Bologna,
Italy, via Tolara di Sopra, 50, 40064 - Ozzano dell’Emilia, Bologna,
Italy
| | - Catia Sternini
- CURE/DDRC, Division of Digestive Diseases, Departments Medicine
and Neurobiology, UCLA, Los Angeles, and Veterans Administration Greater Los
Angeles Health System, Bldg 115 Room 223, VAGLAHS, 11301 Wilshire Blvd, Los
Angeles, CA 90073, USA, , Tel:
+1-310-312-9477, Fax: +1-310-825-3133
| | - Paolo Clavenzani
- Department of Veterinary Medical Science, University of Bologna,
Italy, via Tolara di Sopra, 50, 40064 - Ozzano dell’Emilia, Bologna,
Italy
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12
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Acid-sensing ion channels (ASICs) in the taste buds of adult zebrafish. Neurosci Lett 2013; 536:35-40. [DOI: 10.1016/j.neulet.2013.01.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 12/12/2012] [Accepted: 01/02/2013] [Indexed: 11/17/2022]
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13
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Clark AA, Liggett SB, Munger SD. Extraoral bitter taste receptors as mediators of off-target drug effects. FASEB J 2012; 26:4827-31. [PMID: 22964302 DOI: 10.1096/fj.12-215087] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We present a novel hypothesis that could explain many off-target effects of diverse pharmaceuticals. Specifically, we propose that any drug with a bitter taste could have unintended actions in the body through stimulation of extraoral type 2 taste receptors (T2Rs). T2Rs were first identified in the oral cavity, where they function as bitter taste receptors. However, recent findings indicate that they are also expressed outside the gustatory system, including in the gastrointestinal and respiratory systems. T2R ligands include a diverse array of natural and synthetic compounds, many of which are toxins. Notably, many pharmaceuticals taste bitter, with compounds such as chloroquine, haloperidol, erythromycin, procainamide, and ofloxacin known to activate T2Rs. Bitter-tasting compounds can have specific physiological effects in T2R-expressing cells. For example, T2Rs are found in some gastrointestinal endocrine cells, including those that secrete the peptide hormones (e.g., ghrelin and glucagon-like peptide-1) in response to stimulation by bitter-tasting compounds. In the respiratory system, stimulation of T2Rs expressed in respiratory epithelia and smooth muscle has been implicated in protective airway reflexes, ciliary beating, and bronchodilation. If our hypothesis is confirmed, it would offer a new paradigm for understanding the off-target actions of diverse drugs and could reveal potential new therapeutic targets.
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Affiliation(s)
- Adam A Clark
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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14
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Abstract
The responses of neural elements in many sensory areas of the brain vary systematically with their physical position, leading to a topographic representation of the outside world. Sensory representation in the olfactory system has been harder to decipher, in part because it is difficult to find appropriate metrics to characterize odor space and to sample this space densely. Recent experiments have shown that the arrangement of glomeruli, the elementary units of processing, is relatively invariant across individuals in a species, yet it is flexible enough to accommodate new sensors that might be added. Evidence supports the existence of coarse spatial domains carved out on a genetic or functional basis, but a systematic organization of odor responses or neural circuits on a local scale is not evident. Experiments and theory that relate the properties of odorant receptors to the detailed wiring diagram of the downstream olfactory circuits and to behaviors they trigger may reveal the design principles that have emerged during evolution.
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Affiliation(s)
- Venkatesh N Murthy
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, USA.
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15
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Abstract
The sense of taste is a specialized chemosensory system dedicated to the evaluation of food and drink. Despite the fact that vertebrates and insects have independently evolved distinct anatomic and molecular pathways for taste sensation, there are clear parallels in the organization and coding logic between the two systems. There is now persuasive evidence that tastant quality is mediated by labeled lines, whereby distinct and strictly segregated populations of taste receptor cells encode each of the taste qualities.
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Affiliation(s)
- David A. Yarmolinsky
- Department of Biochemistry and Molecular Biophysics and Department of Neuroscience, Howard Hughes Medical Institute, Columbia College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Charles S. Zuker
- Department of Biochemistry and Molecular Biophysics and Department of Neuroscience, Howard Hughes Medical Institute, Columbia College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
- Correspondence:
| | - Nicholas J.P. Ryba
- National Institute of Dental and Craniofacial Research (NIDCR), Bethesda, MD 20892, USA
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