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Abstract
The study of taste has been guided throughout much of its history by the conceptual framework of psychophysics, where the focus was on quantification of the subjective experience of the taste sensations. By the mid-20th century, data from physiologic studies had accumulated sufficiently to assemble a model for the function of receptors that must mediate the initial stimulus of tastant molecules in contact with the tongue. But the study of taste as a receptor-mediated event did not gain momentum until decades later when the actual receptor proteins and attendant signaling mechanisms were identified and localized to the highly specialized taste-responsive cells of the tongue. With those discoveries a new opportunity to examine taste as a function of receptor activity has come into focus. Pharmacology is the science designed specifically for the experimental interrogation and quantitative characterization of receptor function at all levels of inquiry from molecules to behavior. This review covers the history of some of the major concepts that have shaped thinking and experimental approaches to taste, the seminal discoveries that have led to elucidation of receptors for taste, and how applying principles of receptor pharmacology can enhance understanding of the mechanisms of taste physiology and perception.
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Affiliation(s)
- R Kyle Palmer
- Opertech Bio, Inc., Pennovation Center, Philadelphia, Pennsylvania
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52
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Schier LA, Spector AC. The Functional and Neurobiological Properties of Bad Taste. Physiol Rev 2019; 99:605-663. [PMID: 30475657 PMCID: PMC6442928 DOI: 10.1152/physrev.00044.2017] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 05/18/2018] [Accepted: 06/30/2018] [Indexed: 12/12/2022] Open
Abstract
The gustatory system serves as a critical line of defense against ingesting harmful substances. Technological advances have fostered the characterization of peripheral receptors and have created opportunities for more selective manipulations of the nervous system, yet the neurobiological mechanisms underlying taste-based avoidance and aversion remain poorly understood. One conceptual obstacle stems from a lack of recognition that taste signals subserve several behavioral and physiological functions which likely engage partially segregated neural circuits. Moreover, although the gustatory system evolved to respond expediently to broad classes of biologically relevant chemicals, innate repertoires are often not in register with the actual consequences of a food. The mammalian brain exhibits tremendous flexibility; responses to taste can be modified in a specific manner according to bodily needs and the learned consequences of ingestion. Therefore, experimental strategies that distinguish between the functional properties of various taste-guided behaviors and link them to specific neural circuits need to be applied. Given the close relationship between the gustatory and visceroceptive systems, a full reckoning of the neural architecture of bad taste requires an understanding of how these respective sensory signals are integrated in the brain.
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Affiliation(s)
- Lindsey A Schier
- Department of Biological Sciences, University of Southern California , Los Angeles, California ; and Department of Psychology and Program in Neuroscience, Florida State University , Tallahassee, Florida
| | - Alan C Spector
- Department of Biological Sciences, University of Southern California , Los Angeles, California ; and Department of Psychology and Program in Neuroscience, Florida State University , Tallahassee, Florida
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53
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Mura E, Yagi M, Yokota K, Seto E, Matsumiya K, Matsumura Y, Hayashi Y. Tolerance of bitter stimuli and attenuation/accumulation of their bitterness in humans. Biosci Biotechnol Biochem 2018; 82:1539-1549. [DOI: 10.1080/09168451.2018.1484273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
ABSTRACT
Some components of bitterness make key flavor contributions to promote the palatability of foods, whereas other components are recognized as aversive signals to avoid consuming harmful substances. These contradictory behaviors suggest that humans tolerate tastes of bitterants based on certain criteria. Here, we investigated human taste tolerance and sensory cues leading to diverse taste tolerance of bitter compounds. Tolerance of eight bitter compounds, which are typically contained in foods, was evaluated by measuring detection and rejection thresholds. The results revealed that the level of tolerance of each compound was variable, and some compounds showed an acceptable concentration regarding the suprathreshold intensity. Tolerance did not depend on the nutritive value or attenuation and accumulation characteristics of bitterness and bitter taste receptors. These results suggest that the criteria controlling tolerance of bitter compounds may be derived from a complex relationship between the taste quality and cognitive process.
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Affiliation(s)
- Emi Mura
- Graduate School of Agriculture, Kyoto University, Uji, Japan
| | - Minako Yagi
- Graduate School of Agriculture, Kyoto University, Uji, Japan
| | - Kohei Yokota
- Graduate School of Agriculture, Kyoto University, Uji, Japan
| | - Eri Seto
- Graduate School of Agriculture, Kyoto University, Uji, Japan
| | | | | | - Yukako Hayashi
- Graduate School of Agriculture, Kyoto University, Uji, Japan
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54
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Miller CN, Proekt I, von Moltke J, Wells KL, Rajpurkar AR, Wang H, Rattay K, Khan IS, Metzger TC, Pollack JL, Fries AC, Lwin WW, Wigton EJ, Parent AV, Kyewski B, Erle DJ, Hogquist KA, Steinmetz LM, Locksley RM, Anderson MS. Thymic tuft cells promote an IL-4-enriched medulla and shape thymocyte development. Nature 2018; 559:627-631. [PMID: 30022164 PMCID: PMC6062473 DOI: 10.1038/s41586-018-0345-2] [Citation(s) in RCA: 197] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 05/23/2018] [Indexed: 12/15/2022]
Abstract
The thymus is responsible for generating a diverse yet self-tolerant pool of T cells1. Although the thymic medulla consists mostly of developing and mature AIRE+ epithelial cells, recent evidence has suggested that there is far greater heterogeneity among medullary thymic epithelial cells than was previously thought2. Here we describe in detail an epithelial subset that is remarkably similar to peripheral tuft cells that are found at mucosal barriers3. Similar to the periphery, thymic tuft cells express the canonical taste transduction pathway and IL-25. However, they are unique in their spatial association with cornified aggregates, ability to present antigens and expression of a broad diversity of taste receptors. Some thymic tuft cells pass through an Aire-expressing stage and depend on a known AIRE-binding partner, HIPK2, for their development. Notably, the taste chemosensory protein TRPM5 is required for their thymic function through which they support the development and polarization of thymic invariant natural killer T cells and act to establish a medullary microenvironment that is enriched in the type 2 cytokine, IL-4. These findings indicate that there is a compartmentalized medullary environment in which differentiation of a minor and highly specialized epithelial subset has a non-redundant role in shaping thymic function.
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Affiliation(s)
- Corey N Miller
- Diabetes Center, University of California, San Francisco, San Francisco, CA, USA
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Irina Proekt
- Diabetes Center, University of California, San Francisco, San Francisco, CA, USA
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Jakob von Moltke
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Kristen L Wells
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Aparna R Rajpurkar
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Haiguang Wang
- Center for Immunology, Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA
| | - Kristin Rattay
- Division of Developmental Immunology, Tumor Immunology Program, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Division of Immunology, Harvard Medical School, Boston, MA, USA
| | - Imran S Khan
- Diabetes Center, University of California, San Francisco, San Francisco, CA, USA
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Todd C Metzger
- Diabetes Center, University of California, San Francisco, San Francisco, CA, USA
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
- Bristol-Myers Squibb, Sunnyvale, CA, USA
| | - Joshua L Pollack
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
- Pionyr Immunotherapeutics, San Francisco, CA, USA
| | - Adam C Fries
- Biological Imaging Development Center and Department of Pathology, University of California, San Francisco, CA, USA
| | - Wint W Lwin
- Diabetes Center, University of California, San Francisco, San Francisco, CA, USA
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Eric J Wigton
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Audrey V Parent
- Diabetes Center, University of California, San Francisco, San Francisco, CA, USA
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Bruno Kyewski
- Division of Developmental Immunology, Tumor Immunology Program, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - David J Erle
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Kristin A Hogquist
- Center for Immunology, Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA
| | - Lars M Steinmetz
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Richard M Locksley
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Mark S Anderson
- Diabetes Center, University of California, San Francisco, San Francisco, CA, USA.
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA.
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA.
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55
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Schroer AB, Gross JD, Kaski SW, Wix K, Siderovski DP, Vandenbeuch A, Setola V. Development of Full Sweet, Umami, and Bitter Taste Responsiveness Requires Regulator of G protein Signaling-21 (RGS21). Chem Senses 2018; 43:367-378. [PMID: 29701767 PMCID: PMC6276893 DOI: 10.1093/chemse/bjy024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The mammalian tastes of sweet, umami, and bitter are initiated by activation of G protein-coupled receptors (GPCRs) of the T1R and T2R families on taste receptor cells. GPCRs signal via nucleotide exchange and hydrolysis, the latter hastened by GTPase-accelerating proteins (GAPs) that include the Regulators of G protein Signaling (RGS) protein family. We previously reported that RGS21, uniquely expressed in Type II taste receptor cells, decreases the potency of bitter-stimulated T2R signaling in cultured cells, consistent with its in vitro GAP activity. However, the role of RGS21 in organismal responses to GPCR-mediated tastants was not established. Here, we characterized mice lacking the Rgs21 fifth exon. Eliminating Rgs21 expression had no effect on body mass accumulation (a measure of alimentation), fungiform papillae number and morphology, circumvallate papillae morphology, and taste bud number. Two-bottle preference tests, however, revealed that Rgs21-null mice have blunted aversion to quinine and denatonium, and blunted preference for monosodium glutamate, the sweeteners sucrose and SC45647, and (surprisingly) NaCl. Observed reductions in GPCR-mediated tastant responses upon Rgs21 loss are opposite to original expectations, given that loss of RGS21-a GPCR signaling negative regulator-should lead to increased responsiveness to tastant-mediated GPCR signaling (all else being equal). Yet, reduced organismal tastant responses are consistent with observations of reduced chorda tympani nerve recordings in Rgs21-null mice. Reduced tastant-mediated responses and behaviors exhibited by adult mice lacking Rgs21 expression since birth have thus revealed an underappreciated requirement for a GPCR GAP to establish the full character of tastant signaling.
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Affiliation(s)
- Adam B Schroer
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Joshua D Gross
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Shane W Kaski
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Kim Wix
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - David P Siderovski
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Aurelie Vandenbeuch
- Department of Otolaryngology, University of Colorado - Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Vincent Setola
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
- Department of Behavioral Medicine and Psychiatry, West Virginia School of Medicine, Morgantown, WV, USA
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56
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Activation of intestinal tuft cell-expressed Sucnr1 triggers type 2 immunity in the mouse small intestine. Proc Natl Acad Sci U S A 2018; 115:5552-5557. [PMID: 29735652 DOI: 10.1073/pnas.1720758115] [Citation(s) in RCA: 177] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The hallmark features of type 2 mucosal immunity include intestinal tuft and goblet cell expansion initiated by tuft cell activation. How infectious agents that induce type 2 mucosal immunity are detected by tuft cells is unknown. Published microarray analysis suggested that succinate receptor 1 (Sucnr1) is specifically expressed in tuft cells. Thus, we hypothesized that the succinate-Sucnr1 axis may be utilized by tuft cells to detect certain infectious agents. Here we confirmed that Sucnr1 is specifically expressed in intestinal tuft cells but not in other types of intestinal epithelial cells, and demonstrated that dietary succinate induces tuft and goblet cell hyperplasia via Sucnr1 and the tuft cell-expressed chemosensory signaling elements gustducin and Trpm5. Conventional mice with a genetic Sucnr1 deficiency (Sucnr1-/-) showed diminished immune responses to treatment with polyethylene glycol and streptomycin, which are known to enhance microbiota-derived succinate, but responded normally to inoculation with the parasitic worm Nippostrongylus brasiliensis that also produces succinate. Thus, Sucnr1 is required for microbiota-induced but not for a generalized worm-induced type 2 immunity.
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57
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Pluskal T, Weng JK. Natural product modulators of human sensations and mood: molecular mechanisms and therapeutic potential. Chem Soc Rev 2018; 47:1592-1637. [PMID: 28933478 DOI: 10.1039/c7cs00411g] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Humans perceive physical information about the surrounding environment through their senses. This physical information is registered by a collection of highly evolved and finely tuned molecular sensory receptors. A multitude of bioactive, structurally diverse ligands have evolved in nature that bind these molecular receptors. The complex, dynamic interactions between the ligands and the receptors lead to changes in our sensory perception or mood. Here, we review our current knowledge of natural products and their derived analogues that interact specifically with human G protein-coupled receptors, ion channels, and nuclear hormone receptors to modulate the sensations of taste, smell, temperature, pain, and itch, as well as mood and its associated behaviour. We discuss the molecular and structural mechanisms underlying such interactions and highlight cases where subtle differences in natural product chemistry produce drastic changes in functional outcome. We also discuss cases where a single compound triggers complex sensory or behavioural changes in humans through multiple mechanistic targets. Finally, we comment on the therapeutic potential of the reviewed area of research and draw attention to recent technological developments in genomics, metabolomics, and metabolic engineering that allow us to tap the medicinal properties of natural product chemistry without taxing nature.
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Affiliation(s)
- Tomáš Pluskal
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA.
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58
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Fu Z, Ogura T, Luo W, Lin W. ATP and Odor Mixture Activate TRPM5-Expressing Microvillous Cells and Potentially Induce Acetylcholine Release to Enhance Supporting Cell Endocytosis in Mouse Main Olfactory Epithelium. Front Cell Neurosci 2018; 12:71. [PMID: 29615870 PMCID: PMC5869921 DOI: 10.3389/fncel.2018.00071] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/27/2018] [Indexed: 12/13/2022] Open
Abstract
The main olfactory epithelium (MOE) functions to detect odor molecules, provide an epithelial surface barrier, and remove xenobiotics from inhaled air. Mechanisms coordinating the activities of different cell types within the MOE to maintain these functions are poorly understood. Previously, we showed that superficially located microvillous cells (MCs) in the MOE expressing transient receptor potential channel M5 (TRPM5) are cholinergic and chemoresponsive and that they play an important role in maintaining odor responses and olfactory-guided behavior under challenging chemical environment. Here we investigated TRPM5-MC activation and subsequent paracrine regulation. Ca2+ imaging showed that TRPM5-MCs dose-dependently increase their intracellular Ca2+ levels in response to ATP, an important signaling molecule for airway mucociliary movement, and to an odor mixture. Pharmacological examination showed that the ATP responses are primarily mediated by P2X purinergic receptors. Interestingly, using the endocytosis dye pHrodo Red dextran, we found that chemical-activated TRPM5-MCs significantly increase the number of pHrodo-labeled puncta compared to controls without stimulation and compared to cells that do not respond to ATP or to the odor mixture. These results indicate potential vesicle recycling after release of the signaling molecule acetylcholine (ACh). Interestingly, TRPM5 knockout (KO) results in a decrease in ATP-induced pHrodo internalization. We further investigated cholinergic regulation of neighboring supporting cells (SCs). We found that ACh strongly elevates intracellular Ca2+ and potentiates pHrodo endocytosis in SCs. The ACh effects are diminished in the presence of atropine or M3 muscarinic receptor antagonist and in SCs lacking M3 receptors. Collectively, these data suggest that TRPM5-MCs may regulate the MOE’s multicellular network activity via cholinergic paracrine signaling for functional maintenance and adaptive plasticity.
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Affiliation(s)
- Ziying Fu
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, United States
| | - Tatsuya Ogura
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, United States
| | - Wangmei Luo
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, United States
| | - Weihong Lin
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, United States
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59
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Association Between Arachidonic Acid and Chicken Meat and Egg Flavor, and Their Genetic Regulation. J Poult Sci 2018; 55:163-171. [PMID: 32055170 PMCID: PMC6756496 DOI: 10.2141/jpsa.0170123] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/01/2017] [Indexed: 02/03/2023] Open
Abstract
In Japan, the majority of chicken meat is obtained from fast-growing broiler chickens. Because most Japanese chicken breeds have a low meat yield and egg production, many of these breeds are endangered. Recently, the palatability of meat and eggs of native chickens has been reevaluated in the Japanese market. Jidori, which means chicken from the local, is an indigenous local chicken that is more delicious, firmer in texture, and more expensive than the broiler chickens. Most Japanese consumers recognize that the meat of Jidori chicken is richer in flavor than that of the broiler chicken. However, the reason for this rich flavor of the meat of Jidori chicken has not been elucidated. Recently, we found that arachidonic acid (AA) (C20:4n-6), a polyunsaturated fatty acid, is associated with the rich flavor of the meat and eggs of Jidori chicken. The present paper summarizes the discovery of the involvement of AA in the flavor characteristic of the meat and eggs of chicken, and also the genetic regulation of the AA content in the meat and eggs of Jidori chicken.
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60
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Vennekens R, Mesuere M, Philippaert K. TRPM5 in the battle against diabetes and obesity. Acta Physiol (Oxf) 2018; 222. [PMID: 28834354 DOI: 10.1111/apha.12949] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 06/06/2017] [Accepted: 08/09/2017] [Indexed: 12/22/2022]
Abstract
TRPM5 is a non-selective monovalent cation channel activated by increases in intracellular Ca2+ . It has a distinct expression pattern: expression is detected in chemosensitive tissues from solitary chemosensory cells to the taste receptor cells and in pancreatic β-cells. The role of TRPM5 has been investigated with the use of knockout mouse models. Trpm5-/- mice have a lack of type II taste perception and show reduced glucose-induced insulin secretion. Expression levels of TRPM5 are reduced in obese, leptin-signalling-deficient mice, and mutations in TRPM5 have been associated with type II diabetes and metabolic syndrome. In this review, we aim to give an overview of the activation, selectivity, modulation and physiological roles of TRPM5.
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Affiliation(s)
- R. Vennekens
- VIB Center for Brain & Disease Research; Leuven Belgium
- Laboratory of Ion Channel Research; TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine; KU Leuven, Leuven Belgium
| | - M. Mesuere
- VIB Center for Brain & Disease Research; Leuven Belgium
- Laboratory of Ion Channel Research; TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine; KU Leuven, Leuven Belgium
| | - K. Philippaert
- VIB Center for Brain & Disease Research; Leuven Belgium
- Laboratory of Ion Channel Research; TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine; KU Leuven, Leuven Belgium
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61
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Dutta Banik D, Martin LE, Freichel M, Torregrossa AM, Medler KF. TRPM4 and TRPM5 are both required for normal signaling in taste receptor cells. Proc Natl Acad Sci U S A 2018; 115:E772-E781. [PMID: 29311301 PMCID: PMC5789955 DOI: 10.1073/pnas.1718802115] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Peripheral taste receptor cells use multiple signaling pathways to transduce taste stimuli into output signals that are sent to the brain. Transient receptor potential melastatin 5 (TRPM5), a sodium-selective TRP channel, functions as a common downstream component in sweet, bitter, and umami signaling pathways. In the absence of TRPM5, mice have a reduced, but not abolished, ability to detect stimuli, suggesting that a TRPM5-independent pathway also contributes to these signals. Here, we identify a critical role for the sodium-selective TRP channel TRPM4 in taste transduction. Using live cell imaging and behavioral studies in KO mice, we show that TRPM4 and TRPM5 are both involved in taste-evoked signaling. Loss of either channel significantly impairs taste, and loss of both channels completely abolishes the ability to detect bitter, sweet, or umami stimuli. Thus, both TRPM4 and TRPM5 are required for transduction of taste stimuli.
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Affiliation(s)
| | - Laura E Martin
- Department of Psychology, University at Buffalo, Buffalo, NY 14260
| | - Marc Freichel
- Pharmakologisches Institut, Universität Heidelberg, D-69120 Heidelberg, Germany
| | | | - Kathryn F Medler
- Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260;
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Yoshida Y, Kawabata F, Kawabata Y, Nishimura S, Tabata S. Expression levels of taste-related genes in palate and tongue tip, and involvement of transient receptor potential subfamily M member 5 (TRPM5) in taste sense in chickens. Anim Sci J 2017; 89:441-447. [DOI: 10.1111/asj.12945] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/28/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Yuta Yoshida
- Laboratory of Functional Anatomy; Faculty of Agriculture; Kyushu University; Fukuoka Japan
| | - Fuminori Kawabata
- Laboratory of Functional Anatomy; Faculty of Agriculture; Kyushu University; Fukuoka Japan
| | - Yuko Kawabata
- Laboratory of Functional Anatomy; Faculty of Agriculture; Kyushu University; Fukuoka Japan
| | - Shotaro Nishimura
- Laboratory of Functional Anatomy; Faculty of Agriculture; Kyushu University; Fukuoka Japan
| | - Shoji Tabata
- Laboratory of Functional Anatomy; Faculty of Agriculture; Kyushu University; Fukuoka Japan
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63
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Yoshida R, Takai S, Sanematsu K, Margolskee RF, Shigemura N, Ninomiya Y. Bitter Taste Responses of Gustducin-positive Taste Cells in Mouse Fungiform and Circumvallate Papillae. Neuroscience 2017; 369:29-39. [PMID: 29113930 DOI: 10.1016/j.neuroscience.2017.10.047] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/24/2017] [Accepted: 10/30/2017] [Indexed: 12/22/2022]
Abstract
Bitter taste serves as an important signal for potentially poisonous compounds in foods to avoid their ingestion. Thousands of compounds are estimated to taste bitter and presumed to activate taste receptor cells expressing bitter taste receptors (Tas2rs) and coupled transduction components including gustducin, phospholipase Cβ2 (PLCβ2) and transient receptor potential channel M5 (TRPM5). Indeed, some gustducin-positive taste cells have been shown to respond to bitter compounds. However, there has been no systematic characterization of their response properties to multiple bitter compounds and the role of transduction molecules in these cells. In this study, we investigated bitter taste responses of gustducin-positive taste cells in situ in mouse fungiform (anterior tongue) and circumvallate (posterior tongue) papillae using transgenic mice expressing green fluorescent protein in gustducin-positive cells. The overall response profile of gustducin-positive taste cells to multiple bitter compounds (quinine, denatonium, cyclohexamide, caffeine, sucrose octaacetate, tetraethylammonium, phenylthiourea, L-phenylalanine, MgSO4, and high concentration of saccharin) was not significantly different between fungiform and circumvallate papillae. These bitter-sensitive taste cells were classified into several groups according to their responsiveness to multiple bitter compounds. Bitter responses of gustducin-positive taste cells were significantly suppressed by inhibitors of TRPM5 or PLCβ2. In contrast, several bitter inhibitors did not show any effect on bitter responses of taste cells. These results indicate that bitter-sensitive taste cells display heterogeneous responses and that TRPM5 and PLCβ2 are indispensable for eliciting bitter taste responses of gustducin-positive taste cells.
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Affiliation(s)
- Ryusuke Yoshida
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, Fukuoka 812-8582, Japan; OBT Research Center, Graduate School of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
| | - Shingo Takai
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
| | - Keisuke Sanematsu
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
| | | | - Noriatsu Shigemura
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, Fukuoka 812-8582, Japan; Division of Sensory Physiology, Research and Development Center for Taste and Odor Sensing, Kyushu University, Fukuoka, Japan
| | - Yuzo Ninomiya
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, Fukuoka 812-8582, Japan; Monell Chemical Senses Center, Philadelphia, PA, USA; Division of Sensory Physiology, Research and Development Center for Taste and Odor Sensing, Kyushu University, Fukuoka, Japan
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64
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Wyatt A, Wartenberg P, Candlish M, Krasteva-Christ G, Flockerzi V, Boehm U. Genetic strategies to analyze primary TRP channel-expressing cells in mice. Cell Calcium 2017; 67:91-104. [DOI: 10.1016/j.ceca.2017.05.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 05/15/2017] [Accepted: 05/15/2017] [Indexed: 11/26/2022]
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65
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Mukherjee N, Pal Choudhuri S, Delay RJ, Delay ER. Cellular mechanisms of cyclophosphamide-induced taste loss in mice. PLoS One 2017; 12:e0185473. [PMID: 28950008 PMCID: PMC5614555 DOI: 10.1371/journal.pone.0185473] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 09/13/2017] [Indexed: 11/18/2022] Open
Abstract
Many commonly prescribed chemotherapy drugs such as cyclophosphamide (CYP) have adverse side effects including disruptions in taste which can result in loss of appetite, malnutrition, poorer recovery and reduced quality of life. Previous studies in mice found evidence that CYP has a two-phase disturbance in taste behavior: a disturbance immediately following drug administration and a second which emerges several days later. In this study, we examined the processes by which CYP disturbs the taste system by examining the effects of the drug on taste buds and cells responsible for taste cell renewal using immunohistochemical assays. Data reported here suggest CYP has direct cytotoxic effects on lingual epithelium immediately following administration, causing an early loss of taste sensory cells. Types II and III cells in fungiform taste buds appear to be more susceptible to this effect than circumvallate cells. In addition, CYP disrupts the population of rapidly dividing cells in the basal layer of taste epithelium responsible for taste cell renewal, manifesting a disturbance days later. The loss of these cells temporarily retards the system’s capacity to replace Type II and Type III taste sensory cells that survived the cytotoxic effects of CYP and died at the end of their natural lifespan. The timing of an immediate, direct loss of taste cells and a delayed, indirect loss without replacement of taste sensory cells are broadly congruent with previously published behavioral data reporting two periods of elevated detection thresholds for umami and sucrose stimuli. These findings suggest that chemotherapeutic disturbances in the peripheral mechanisms of the taste system may cause dietary challenges at a time when the cancer patient has significant need for well balanced, high energy nutritional intake.
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Affiliation(s)
- Nabanita Mukherjee
- Department of Biology and Vermont Chemosensory Group, University of Vermont, Burlington, Vermont, United States of America
| | - Shreoshi Pal Choudhuri
- Department of Biology and Vermont Chemosensory Group, University of Vermont, Burlington, Vermont, United States of America
| | - Rona J. Delay
- Department of Biology and Vermont Chemosensory Group, University of Vermont, Burlington, Vermont, United States of America
| | - Eugene R. Delay
- Department of Biology and Vermont Chemosensory Group, University of Vermont, Burlington, Vermont, United States of America
- * E-mail:
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66
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Ekstrand B, Young JF, Rasmussen MK. Taste receptors in the gut - A new target for health promoting properties in diet. Food Res Int 2017; 100:1-8. [PMID: 28888429 DOI: 10.1016/j.foodres.2017.08.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 08/07/2017] [Accepted: 08/12/2017] [Indexed: 12/17/2022]
Abstract
In this review we describe a new target for food functionality, the taste receptors in the gastrointestinal tract. These receptors are involved in an intricate signalling network for monitoring of taste and nutrient intake, homeostasis and energy metabolism, and they are also an early warning system for toxic substances in our diet. Especially the receptors for bitter taste provide a new possibility to activate a number of health related signalling pathways, already at low concentrations of the active substance, without requiring uptake into the body and transport via the circulation. When ligands bind to these receptors, signalling is induced either via peptide hormones into the circulation to other organs in the body, or via nerve fibers directly to the brain.
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Affiliation(s)
- Bo Ekstrand
- Chalmers University of Technology, Department of Biology and Biological Engineering, Food and Nutrition Science, SE-412 96 Gothenburg, Sweden
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67
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Lemon CH. Modulation of taste processing by temperature. Am J Physiol Regul Integr Comp Physiol 2017; 313:R305-R321. [PMID: 28794101 DOI: 10.1152/ajpregu.00089.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 08/01/2017] [Accepted: 08/01/2017] [Indexed: 02/02/2023]
Abstract
Taste stimuli have a temperature that can stimulate thermosensitive neural machinery in the mouth during gustatory experience. Although taste and oral temperature are sometimes discussed as different oral sensory modalities, there is a body of literature that demonstrates temperature is an important component and modulator of the intensity of gustatory neural and perceptual responses. Available data indicate that the influence of temperature on taste, herein referred to as "thermogustation," can vary across taste qualities, can also vary among stimuli presumed to share a common taste quality, and is conditioned on taste stimulus concentration, with neuronal and psychophysical data revealing larger modulatory effects of temperature on gustatory responding to weakened taste solutions compared with concentrated. What is more, thermogustation is evidenced to involve interplay between mouth and stimulus temperature. Given these and other dependencies, identifying principles by which thermal input affects gustatory information flow in the nervous system may be important for ultimately unravelling the organization of neural circuits for taste and defining their involvement with multisensory processing related to flavor. Yet thermal effects are relatively understudied in gustatory neuroscience. Major gaps in our understanding of the mechanisms and consequences of thermogustation include delineating supporting receptors, the potential involvement of oral thermal and somatosensory trigeminal neurons in thermogustatory interactions, and the broader operational roles of temperature in gustatory processing. This review will discuss these and other issues in the context of the literature relevant to understanding thermogustation.
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68
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Camandola S, Mattson MP. Toll-like receptor 4 mediates fat, sugar, and umami taste preference and food intake and body weight regulation. Obesity (Silver Spring) 2017; 25:1237-1245. [PMID: 28500692 PMCID: PMC5487280 DOI: 10.1002/oby.21871] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 03/08/2017] [Accepted: 04/06/2017] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Immune and inflammatory pathways play important roles in the pathogenesis of metabolic disorders. This study investigated the role of toll-like receptor 4 (TLR4) in orosensory detection of dietary lipids and sugars. METHODS Taste preferences of TLR4 knockout (KO) and wild-type (WT) male mice under a standard and a high-fat, high-sugar diet were assessed with two-bottle tests. Gene expression of taste signaling molecules was analyzed in the tongue epithelium. The role of TLR4 in food intake and weight gain was investigated in TLR4 KO and WT mice fed a high-fat and high-sugar diet for 12 weeks. RESULTS Compared to WT mice, TLR4 KO mice showed reduced preference for lipids, sugars, and umami in a two-bottle preference test. The altered taste perception was associated with decreased levels of key taste regulatory molecules in the tongue epithelium. TLR4 KO mice on a high-fat and high-sugar diet consumed less food and drink, resulting in diminished weight gain. CONCLUSIONS TLR4 signaling promotes ingestion of sugar and fat by a mechanism involving increased preference for such obesogenic foods.
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Affiliation(s)
- Simonetta Camandola
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, Baltimore, MD, USA
| | - Mark P. Mattson
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, Baltimore, MD, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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69
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Ciardo MG, Ferrer-Montiel A. Lipids as central modulators of sensory TRP channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1615-1628. [PMID: 28432033 DOI: 10.1016/j.bbamem.2017.04.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 04/13/2017] [Accepted: 04/15/2017] [Indexed: 12/13/2022]
Abstract
The transient receptor potential (TRP) ion channel family is involved in a diversity of physiological processes including sensory and homeostatic functions, as well as muscle contraction and vasomotor control. Their dysfunction contributes to the etiology of several diseases, being validated as therapeutic targets. These ion channels may be activated by physical or chemical stimuli and their function is highly influenced by signaling molecules activated by extracellular signals. Notably, as integral membrane proteins, lipid molecules also modulate their membrane location and function either by direct interaction with the channel structure or by modulating the physico-chemical properties of the cellular membrane. This lipid-based modulatory effect is being considered an alternative and promising approach to regulate TRP channel dysfunction in diseases. Here, we review the current progress in this exciting field highlighting a complex channel regulation by a large diversity of lipid molecules and suggesting some diseases that may benefit from a membrane lipid therapy. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.
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Affiliation(s)
| | - Antonio Ferrer-Montiel
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Av. De la Universidad s/n, Elche, Spain.
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70
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Benford H, Bolborea M, Pollatzek E, Lossow K, Hermans-Borgmeyer I, Liu B, Meyerhof W, Kasparov S, Dale N. A sweet taste receptor-dependent mechanism of glucosensing in hypothalamic tanycytes. Glia 2017; 65:773-789. [PMID: 28205335 PMCID: PMC5363357 DOI: 10.1002/glia.23125] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 02/01/2023]
Abstract
Hypothalamic tanycytes are glial‐like glucosensitive cells that contact the cerebrospinal fluid of the third ventricle, and send processes into the hypothalamic nuclei that control food intake and body weight. The mechanism of tanycyte glucosensing remains undetermined. While tanycytes express the components associated with the glucosensing of the pancreatic β cell, they respond to nonmetabolisable glucose analogues via an ATP receptor‐dependent mechanism. Here, we show that tanycytes in rodents respond to non‐nutritive sweeteners known to be ligands of the sweet taste (Tas1r2/Tas1r3) receptor. The initial sweet tastant‐evoked response, which requires the presence of extracellular Ca2+, leads to release of ATP and a larger propagating Ca2+ response mediated by P2Y1 receptors. In Tas1r2 null mice the proportion of glucose nonresponsive tanycytes was greatly increased in these mice, but a subset of tanycytes retained an undiminished sensitivity to glucose. Our data demonstrate that the sweet taste receptor mediates glucosensing in about 60% of glucosensitive tanycytes while the remaining 40% of glucosensitive tanycytes use some other, as yet unknown mechanism.
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Affiliation(s)
- Heather Benford
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Matei Bolborea
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Eric Pollatzek
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Kristina Lossow
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, Nuthetal, 14558, Germany
| | - Irm Hermans-Borgmeyer
- Transgenic Animal Unit, University Medical Center Hamburg-Eppendorf, Martinistr. 52, Hamburg, 20246, Germany
| | - Beihui Liu
- School of Physiology and Pharmacology, University of Bristol, United Kingdom
| | - Wolfgang Meyerhof
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, Nuthetal, 14558, Germany
| | - Sergey Kasparov
- School of Physiology and Pharmacology, University of Bristol, United Kingdom
| | - Nicholas Dale
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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71
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Trpm5 expression in the olfactory epithelium. Mol Cell Neurosci 2017; 80:75-88. [PMID: 28188885 DOI: 10.1016/j.mcn.2017.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 02/02/2017] [Accepted: 02/05/2017] [Indexed: 11/20/2022] Open
Abstract
The Ca2+-activated monovalent cation channel Trpm5 is a key element in chemotransduction of taste receptor cells of the tongue, but the extent to which Trpm5 channels are expressed in olfactory sensory neurons (OSNs) of the main olfactory epithelium (MOE) of adult mice as part of a specific pheromonal detection system is debated. Here, we used a novel Trpm5-IRES-Cre knockin strain to drive Cre recombinase expression, employed previously validated Trpm5 antibodies, performed in situ hybridization experiments to localize Trpm5 RNA, and searched extensively for Trpm5 splice variants in genetically-labeled, Trpm5-expressing MOE cells. In contrast to previous reports, we find no evidence for the existence in adult mouse OSNs of the classical Trpm5 channel known from taste cells. We show that Trpm5-expressing adult OSNs express a novel Trpm5 splice variant, Trpm5-9, that is unlikely to form a functional cation channel by itself. We also demonstrate that Trpm5 is transiently expressed in a subpopulation of mature OSNs in the embryonic olfactory epithelium, indicating that Trpm5 channels could play a specific role in utero during a narrow developmental time window. Ca2+ imaging with GCaMP3 under the control of the Trpm5-IRES-Cre allele using a newly developed MOE wholemount preparation of the adult olfactory epithelium reveals that Trpm5-GCaMP3 OSNs comprise a heterogeneous group of sensory neurons many of which can detect general odorants. Together, these studies are essential for understanding the role of transient receptor potential channels in mammalian olfaction.
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72
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Respiratory Rhythm Generation: The Whole Is Greater Than the Sum of the Parts. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1015:147-161. [DOI: 10.1007/978-3-319-62817-2_9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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73
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Gerbe F, Jay P. Intestinal tuft cells: epithelial sentinels linking luminal cues to the immune system. Mucosal Immunol 2016; 9:1353-1359. [PMID: 27554294 DOI: 10.1038/mi.2016.68] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 07/08/2016] [Indexed: 02/04/2023]
Abstract
Epithelial tuft cells (also known as "brush" cells in the airway) were first identified morphologically, almost six decades ago in the trachea and gastro-intestinal tract, but their function remained mysterious until three almost simultaneous reports recently revealed their essential role in the initiation of immune type 2 responses. This is a new and exciting example of cooperation between the epithelial and haematopoietic compartments for the management of enteric parasite infections. Here we review tuft cell functions and markers, and anchors epithelial tuft cells within the current paradigm of type 2 immune responses.
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Affiliation(s)
- F Gerbe
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France.,INSERM, U1191, Montpellier, France.,Université de Montpellier, Montpellier, France
| | - P Jay
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France.,INSERM, U1191, Montpellier, France.,Université de Montpellier, Montpellier, France
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74
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Fujiyama R, Toda K. Functional effects of cold stimulation on taste perception in humans. Odontology 2016; 105:275-282. [DOI: 10.1007/s10266-016-0263-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Accepted: 07/19/2016] [Indexed: 01/29/2023]
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75
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Ackroff K, Sclafani A. Maltodextrin and sucrose preferences in sweet-sensitive (C57BL/6J) and subsensitive (129P3/J) mice revisited. Physiol Behav 2016; 165:286-90. [PMID: 27526998 DOI: 10.1016/j.physbeh.2016.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 07/15/2016] [Accepted: 08/11/2016] [Indexed: 12/18/2022]
Abstract
Mice are attracted to the tastes of sugar and maltodextrin solutions. Sugar taste is mediated by the T1R2/T1R3 sweet taste receptor, while maltodextrin taste is dependent upon a different as yet unidentified receptor. In a prior study sweet-sensitive C57BL/6J (B6) mice displayed similar preferences for sucrose and maltodextrin solutions in 24-h saccharide vs. water choice tests that exceeded those of sweet-subsensitive 129P3/J (129) mice. In a subsequent experiment reported here, sucrose and maltodextrin (Polycose) preference and acceptance were compared in the two strains in saccharide vs. saccharide choice tests with isocaloric concentrations (0.5-32%). The 129 mice displayed significantly greater maltodextrin preferences than B6 mice at mid-range concentrations (2-8%), while the mice displayed an opposite preference profile at the highest concentration (32%). As in prior studies, 129 mice consumed less total saccharide than B6 mice at lower concentrations. These findings show that the conclusions reached from tastant vs. water tests may differ from those pitting one tastant against another. The increased sucrose preference and intake of B6 mice, relative to 129 mice, is consistent with their sweet-sensitive phenotype.
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Affiliation(s)
- Karen Ackroff
- Department of Psychology, Brooklyn College and the Graduate School, The City University of New York, Brooklyn, NY 11210, USA.
| | - Anthony Sclafani
- Department of Psychology, Brooklyn College and the Graduate School, The City University of New York, Brooklyn, NY 11210, USA
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76
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Lemon CH, Kang Y, Li J. Separate functions for responses to oral temperature in thermo-gustatory and trigeminal neurons. Chem Senses 2016; 41:457-71. [PMID: 26976122 PMCID: PMC4910675 DOI: 10.1093/chemse/bjw022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Oral temperature is a component and modifier of taste perception. Both trigeminal (V) and taste-sensitive cells, including those in the nucleus of the solitary tract (NTS), can respond to oral temperature. However, functional associations in thermal sensitivity between V and gustatory neurons are poorly understood. To study this we recorded electrophysiological responses to oral stimulation with cool (9, 15, 25, 32, and 34 °C) and warm (40 and 45 °C) temperatures from medullary V (n = 45) and taste-sensitive NTS (n = 27) neurons in anesthetized mice. Results showed temperatures below 34 °C activated the majority of V neurons but only a minority of NTS units. V neurons displayed larger responses to cooling and responded to temperatures that poorly stimulated NTS cells. Multivariate analyses revealed different temperatures induced larger differences in responses across V compared with NTS neurons, indicating V pathways possess greater capacity to signal temperature. Conversely, responses to temperature in NTS units associated with gustatory tuning. Further analyses identified two types of cooling-sensitive V neurons oriented toward innocuous or noxious cooling. Multivariate analyses indicated the combined response of these cells afforded distinction among a broad range of cool temperatures, suggesting multiple types of V neurons work together to represent oral cooling.
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Affiliation(s)
- Christian H Lemon
- Department of Biology, The University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA
| | - Yi Kang
- Department of Biology, The University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA
| | - Jinrong Li
- Department of Biology, The University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA
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77
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Shaik FA, Singh N, Arakawa M, Duan K, Bhullar RP, Chelikani P. Bitter taste receptors: Extraoral roles in pathophysiology. Int J Biochem Cell Biol 2016; 77:197-204. [PMID: 27032752 DOI: 10.1016/j.biocel.2016.03.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 03/16/2016] [Accepted: 03/22/2016] [Indexed: 11/17/2022]
Abstract
Over the past decade tremendous progress has been made in understanding the functional role of bitter taste receptors (T2Rs) and bitter taste perception. This review will cover the recent advances made in identifying the role of T2Rs in pathophysiological states. T2Rs are widely expressed in various parts of human anatomy and have been shown to be involved in physiology of respiratory system, gastrointestinal tract and endocrine system. Empirical evidence has shown T2Rs to be an integral component of antimicrobial immune responses in upper respiratory tract infections. The studies on human airway smooth muscle cells have shown that a potent bitter tastant induced bronchodilatory effects mediated by bitter taste receptors. Clinical data suggests a role for T2R38 polymorphism in predisposition of individuals to chronic rhinosinusitis. The role of genetic variation in T2Rs and its impact on disease susceptibility have been investigated in various other disease risk factors such as alcohol dependence, head and neck cancers. Preliminary reports have demonstrated differential expression of functional T2Rs in breast cancer cell lines. Studies on the role of T2Rs in pathophysiology of diseases including chronic rhinosinusitis, asthma, cystic fibrosis, and cancer have been promising. However, research in this field is in its nascent stages, and more confirmatory studies on animal models and in clinical settings are required.
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Affiliation(s)
- Feroz Ahmed Shaik
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada; Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
| | - Nisha Singh
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada; Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
| | - Makoto Arakawa
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
| | - Kangmin Duan
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada; Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
| | - Rajinder P Bhullar
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
| | - Prashen Chelikani
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada; Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB R3E 0W2, Canada.
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78
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Howitt MR, Lavoie S, Michaud M, Blum AM, Tran SV, Weinstock JV, Gallini CA, Redding K, Margolskee RF, Osborne LC, Artis D, Garrett WS. Tuft cells, taste-chemosensory cells, orchestrate parasite type 2 immunity in the gut. Science 2016; 351:1329-33. [PMID: 26847546 PMCID: PMC5528851 DOI: 10.1126/science.aaf1648] [Citation(s) in RCA: 615] [Impact Index Per Article: 76.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 01/27/2016] [Indexed: 12/26/2022]
Abstract
The intestinal epithelium forms an essential barrier between a host and its microbiota. Protozoa and helminths are members of the gut microbiota of mammals, including humans, yet the many ways that gut epithelial cells orchestrate responses to these eukaryotes remain unclear. Here we show that tuft cells, which are taste-chemosensory epithelial cells, accumulate during parasite colonization and infection. Disruption of chemosensory signaling through the loss of TRMP5 abrogates the expansion of tuft cells, goblet cells, eosinophils, and type 2 innate lymphoid cells during parasite colonization. Tuft cells are the primary source of the parasite-induced cytokine interleukin-25, which indirectly induces tuft cell expansion by promoting interleukin-13 production by innate lymphoid cells. Our results identify intestinal tuft cells as critical sentinels in the gut epithelium that promote type 2 immunity in response to intestinal parasites.
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Affiliation(s)
- Michael R Howitt
- Departments of Immunology and Infectious Diseases and Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Sydney Lavoie
- Departments of Immunology and Infectious Diseases and Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Monia Michaud
- Departments of Immunology and Infectious Diseases and Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Arthur M Blum
- Division of Gastroenterology, Tufts Medical Center, Boston, MA 02111, USA
| | - Sara V Tran
- Monell Chemical Senses Center, Philadelphia, PA 19104, USA
| | - Joel V Weinstock
- Division of Gastroenterology, Tufts Medical Center, Boston, MA 02111, USA
| | - Carey Ann Gallini
- Departments of Immunology and Infectious Diseases and Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Kevin Redding
- Monell Chemical Senses Center, Philadelphia, PA 19104, USA
| | | | - Lisa C Osborne
- Jill Roberts Institute for Research in Inflammatory Bowel Disease, Weill Cornell Medical College, Cornell University, New York, NY 10021, USA
| | - David Artis
- Jill Roberts Institute for Research in Inflammatory Bowel Disease, Weill Cornell Medical College, Cornell University, New York, NY 10021, USA
| | - Wendy S Garrett
- Departments of Immunology and Infectious Diseases and Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA. Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142, USA. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
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79
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Recent Advances in Molecular Mechanisms of Taste Signaling and Modifying. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 323:71-106. [PMID: 26944619 DOI: 10.1016/bs.ircmb.2015.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The sense of taste conveys crucial information about the quality and nutritional value of foods before it is ingested. Taste signaling begins with taste cells via taste receptors in oral cavity. Activation of these receptors drives the transduction systems in taste receptor cells. Then particular transmitters are released from the taste cells and activate corresponding afferent gustatory nerve fibers. Recent studies have revealed that taste sensitivities are defined by distinct taste receptors and modulated by endogenous humoral factors in a specific group of taste cells. Such peripheral taste generations and modifications would directly influence intake of nutritive substances. This review will highlight current understanding of molecular mechanisms for taste reception, signal transduction in taste bud cells, transmission between taste cells and nerves, regeneration from taste stem cells, and modification by humoral factors at peripheral taste organs.
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80
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Cherkashin AP, Kolesnikova AS, Tarasov MV, Romanov RA, Rogachevskaja OA, Bystrova MF, Kolesnikov SS. Expression of calcium-activated chloride channels Ano1 and Ano2 in mouse taste cells. Pflugers Arch 2015; 468:305-19. [DOI: 10.1007/s00424-015-1751-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/20/2015] [Accepted: 10/23/2015] [Indexed: 02/03/2023]
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81
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Poole RL, Aleman TR, Ellis HT, Tordoff MG. Maltodextrin Acceptance and Preference in Eight Mouse Strains. Chem Senses 2015; 41:45-52. [PMID: 26464499 DOI: 10.1093/chemse/bjv056] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Rodents are strongly attracted to the taste(s) of maltodextrins. A first step toward discovery of the underlying genes involves identifying phenotypic differences among inbred strains of mice. To do this, we used 5-s brief-access tests and 48-h 2-bottle choice tests to survey the avidity for the maltodextrin, Maltrin M040, of mice from 8 inbred strains (129S1/SvImJ, A/J, CAST/EiJ, C57BL/6J, NOD/ShiLTJ, NZO/HlLtJ, PWK/PhJ, and WSB/EiJ). In brief-access tests, the CAST and PWK strains licked significantly less maltodextrin than equivalent concentrations of sucrose, whereas the other strains generally licked the 2 carbohydrates equally. Similarly, in 2-bottle choice tests, the CAST and PWK strains drank less 4% maltodextrin than 4% sucrose, whereas the other strains had similar intakes of these 2 solutions; the CAST and PWK strains did not differ from the C57, NOD, or NZO strains in 4% sucrose intake. In sum, we have identified strain variation in maltodextrin perception that is distinct from variation in sucrose perception. The phenotypic variation characterized here will aid in identifying genes responsible for maltodextrin acceptance. Our results identify C57 × PWK mice or NZO × CAST mice as informative crosses to produce segregating hybrids that will expose quantitative trait loci underlying maltodextrin acceptance and preference.
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Affiliation(s)
- Rachel L Poole
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Tiffany R Aleman
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Hillary T Ellis
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Michael G Tordoff
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
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Ablation of TRPM5 in Mice Results in Reduced Body Weight Gain and Improved Glucose Tolerance and Protects from Excessive Consumption of Sweet Palatable Food when Fed High Caloric Diets. PLoS One 2015; 10:e0138373. [PMID: 26397098 PMCID: PMC4580452 DOI: 10.1371/journal.pone.0138373] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 08/27/2015] [Indexed: 01/09/2023] Open
Abstract
The calcium activated cation channel transient receptor potential channel type M5 (TRPM5) is part of the downstream machinery of the taste receptors and have been shown to play a central role in taste signalling. In addition it is also found in other types of chemosensory cells in various parts of the body as well as in pancreatic β-cells. The aim of this study was to investigate the effects of TRPM5 gene ablation on body weight, insulin sensitivity and other metabolic parameters in long-term high caloric diet induced obesity. Trpm5-/- mice gained significantly less body weight and fat mass on both palatable carbohydrate and fat rich cafeteria diet and 60% high fat diet (HFD) and developed less insulin resistance compared to wild type mice. A main finding was the clearly improved glucose tolerance in Trpm5-/- mice compared to wild type mice on cafeteria diet, which was independent of body weight. In addition, it was shown that Trpm5-/- mice consumed the same amount of calories when fed a HFD only or a HFD in combination with a palatable chocolate ball, which is in contrast to wild type mice that increased their caloric intake when fed the combination, mainly due to excessive consumption of the chocolate ball. Thus the palatable sugar containing diet induced overeating was prevented in Trpm5-/- mice. This indicates that sweet taste induced overeating may be a cause for the increased energy intake and glucose intolerance development seen for wild type mice on a sugar and high fat rich cafeteria diet compared to when on a high fat diet. This study point to an important role for the taste signalling system and TRPM5 in diet induced glucose intolerance.
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83
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Nicotinic Acetylcholine Receptor (nAChR) Dependent Chorda Tympani Taste Nerve Responses to Nicotine, Ethanol and Acetylcholine. PLoS One 2015; 10:e0127936. [PMID: 26039516 PMCID: PMC4454666 DOI: 10.1371/journal.pone.0127936] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/20/2015] [Indexed: 12/12/2022] Open
Abstract
Nicotine elicits bitter taste by activating TRPM5-dependent and TRPM5-independent but neuronal nAChR-dependent pathways. The nAChRs represent common targets at which acetylcholine, nicotine and ethanol functionally interact in the central nervous system. Here, we investigated if the nAChRs also represent a common pathway through which the bitter taste of nicotine, ethanol and acetylcholine is transduced. To this end, chorda tympani (CT) taste nerve responses were monitored in rats, wild-type mice and TRPM5 knockout (KO) mice following lingual stimulation with nicotine free base, ethanol, and acetylcholine, in the absence and presence of nAChR agonists and antagonists. The nAChR modulators: mecamylamine, dihydro-β-erythroidine, and CP-601932 (a partial agonist of the α3β4* nAChR), inhibited CT responses to nicotine, ethanol, and acetylcholine. CT responses to nicotine and ethanol were also inhibited by topical lingual application of 8-chlorophenylthio (CPT)-cAMP and loading taste cells with [Ca2+]i by topical lingual application of ionomycin + CaCl2. In contrast, CT responses to nicotine were enhanced when TRC [Ca2+]i was reduced by topical lingual application of BAPTA-AM. In patch-clamp experiments, only a subset of isolated rat fungiform taste cells exposed to nicotine responded with an increase in mecamylamine-sensitive inward currents. We conclude that nAChRs expressed in a subset of taste cells serve as common receptors for the detection of the TRPM5-independent bitter taste of nicotine, acetylcholine and ethanol.
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84
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McCutcheon JE. The role of dopamine in the pursuit of nutritional value. Physiol Behav 2015; 152:408-15. [PMID: 25957911 DOI: 10.1016/j.physbeh.2015.05.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 04/28/2015] [Accepted: 05/04/2015] [Indexed: 01/16/2023]
Abstract
Acquiring enough food to meet energy expenditure is fundamental for all organisms. Thus, mechanisms have evolved to allow foods with high nutritional value to be readily detected, consumed, and remembered. Although taste is often involved in these processes, there is a wealth of evidence supporting the existence of taste-independent nutrient sensing. In particular, post-ingestive mechanisms arising from the arrival of nutrients in the gut are able to drive food intake and behavioural conditioning. The physiological mechanisms underlying these effects are complex but are believed to converge on mesolimbic dopamine signalling to translate post-ingestive sensing of nutrients into reward and reinforcement value. Discerning the role of nutrition is often difficult because food stimulates sensory systems and post-ingestive pathways in concert. In this mini-review, I discuss the various methods that may be used to study post-ingestive processes in isolation including sham-feeding, non-nutritive sweeteners, post-ingestive infusions, and pharmacological and genetic methods. Using this structure, I present the evidence that dopamine is sensitive to nutritional value of certain foods and examine how this affects learning about food, the role of taste, and the implications for human obesity.
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Affiliation(s)
- James Edgar McCutcheon
- Dept. of Cell Physiology and Pharmacology, Maurice Shock Medical Sciences Building, University of Leicester, University Road, Leicester LE1 9HN, United Kingdom.
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85
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Kusumakshi S, Voigt A, Hübner S, Hermans-Borgmeyer I, Ortalli A, Pyrski M, Dörr J, Zufall F, Flockerzi V, Meyerhof W, Montmayeur JP, Boehm U. A Binary Genetic Approach to Characterize TRPM5 Cells in Mice. Chem Senses 2015; 40:413-25. [PMID: 25940069 DOI: 10.1093/chemse/bjv023] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Transient receptor potential channel subfamily M member 5 (TRPM5) is an important downstream signaling component in a subset of taste receptor cells making it a potential target for taste modulation. Interestingly, TRPM5 has been detected in extra-oral tissues; however, the function of extra-gustatory TRPM5-expressing cells is less well understood. To facilitate visualization and manipulation of TRPM5-expressing cells in mice, we generated a Cre knock-in TRPM5 allele by homologous recombination. We then used the novel TRPM5-IRES-Cre mouse strain to report TRPM5 expression by activating a τGFP transgene. To confirm faithful coexpression of τGFP and TRPM5 we generated and validated a new anti-TRPM5 antiserum enabling us to analyze acute TRPM5 protein expression. τGFP cells were found in taste bud cells of the vallate, foliate, and fungiform papillae as well as in the palate. We also detected TRPM5 expression in several other tissues such as in the septal organ of Masera. Interestingly, in the olfactory epithelium of adult mice acute TRPM5 expression was detected in only one (short microvillar cells) of two cell populations previously reported to express TRPM5. The TRPM5-IC mouse strain described here represents a novel genetic tool and will facilitate the study and tissue-specific manipulation of TRPM5-expressing cells in vivo.
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Affiliation(s)
- Soumya Kusumakshi
- Department of Pharmacology and Toxicology, University of Saarland, School of Medicine, 66421 Homburg, Germany
| | - Anja Voigt
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
| | - Sandra Hübner
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
| | - Irm Hermans-Borgmeyer
- Transgenic Animals Service Group, UKE, Center for Molecular Neurobiology Hamburg (ZMNH), Falkenried 94, 20251 Hamburg, Germany
| | - Ana Ortalli
- Department of Pharmacology and Toxicology, University of Saarland, School of Medicine, 66421 Homburg, Germany, Centre des Sciences du Goût et de l'Alimentation, UMR6265 CNRS, UMR1324 INRA, Université de Bourgogne, 9E Boulevard Jeanne D'Arc, 21000 Dijon, France and
| | - Martina Pyrski
- Department of Physiology, University of Saarland, School of Medicine, 66421 Homburg, Germany
| | - Janka Dörr
- Department of Pharmacology and Toxicology, University of Saarland, School of Medicine, 66421 Homburg, Germany
| | - Frank Zufall
- Department of Physiology, University of Saarland, School of Medicine, 66421 Homburg, Germany
| | - Veit Flockerzi
- Department of Pharmacology and Toxicology, University of Saarland, School of Medicine, 66421 Homburg, Germany
| | - Wolfgang Meyerhof
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
| | - Jean-Pierre Montmayeur
- Centre des Sciences du Goût et de l'Alimentation, UMR6265 CNRS, UMR1324 INRA, Université de Bourgogne, 9E Boulevard Jeanne D'Arc, 21000 Dijon, France and
| | - Ulrich Boehm
- Department of Pharmacology and Toxicology, University of Saarland, School of Medicine, 66421 Homburg, Germany,
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87
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Li J, Lemon CH. Influence of stimulus and oral adaptation temperature on gustatory responses in central taste-sensitive neurons. J Neurophysiol 2015; 113:2700-12. [PMID: 25673737 DOI: 10.1152/jn.00736.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 02/05/2015] [Indexed: 01/19/2023] Open
Abstract
The temperature of taste stimuli can modulate gustatory processing. Perceptual data indicate that the adapted temperature of oral epithelia also influences gustation, although little is known about the neural basis of this effect. Here, we electrophysiologically recorded orosensory responses (spikes) to 25°C (cool) and 35°C (warm) solutions of sucrose (0.1 and 0.3 M), NaCl (0.004, 0.1, and 0.3 M), and water from taste-sensitive neurons in the nucleus of the solitary tract in mice under varied thermal adaptation of oral epithelia. Conditions included presentation of taste stimuli isothermal to adaptation temperatures of 25°C (constant cooling) and 35°C (constant warming), delivery of 25°C stimuli following 35°C adaptation (relative cooling), and presentation of 35°C stimuli following 25°C adaptation (relative warming). Responses to sucrose in sucrose-oriented cells (n = 15) were enhanced under the constant and relative warming conditions compared with constant cooling, where contiguous cooling across adaptation and stimulus periods induced the lowest and longest latency responses to sucrose. Yet compared with constant warming, cooling sucrose following warm adaptation (relative cooling) only marginally reduced activity to 0.1 M sucrose and did not alter responses to 0.3 M sucrose. Thus, warmth adaptation counteracted the attenuation in sucrose activity associated with stimulus cooling. Analysis of sodium-oriented (n = 25) neurons revealed adaptation to cool water, and cooling taste solutions enhanced unit firing to 0.004 M (perithreshold) NaCl, whereas warmth adaptation and stimulus warming could facilitate activity to 0.3 M NaCl. The concentration dependence of this thermal effect may reflect a dual effect of temperature on the sodium reception mechanism that drives sodium-oriented cells.
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Affiliation(s)
- Jinrong Li
- Department of Biology, University of Oklahoma, Norman, Oklahoma
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88
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Shigemura N. Modulation of Taste Responsiveness by Angiotensin II. FOOD SCIENCE AND TECHNOLOGY RESEARCH 2015. [DOI: 10.3136/fstr.21.757] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Noriatsu Shigemura
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University
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89
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Sclafani A, Ackroff K. Flavor preference conditioning by different sugars in sweet ageusic Trpm5 knockout mice. Physiol Behav 2014; 140:156-63. [PMID: 25497884 DOI: 10.1016/j.physbeh.2014.12.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/10/2014] [Accepted: 12/11/2014] [Indexed: 01/05/2023]
Abstract
Knockout (KO) mice missing the taste signaling protein Trpm5 have greatly attenuated sweetener preferences but develop strong preferences for glucose in 24-h tests, which is attributed to post-oral sugar conditioning. Trpm5 KO mice express mild preferences for galactose but no preferences for fructose in 24-h tests, which suggests that these sugars differ in their post-oral reinforcing effects. Here we investigated sugar-conditioned flavor preferences in Trpm5 KO and C57BL/6J wildtype (B6) mice. The mice were trained to consume a flavored (CS+, e.g. grape) 8% sugar solution and flavored (CS-, e.g., cherry) water on alternating days followed by two-bottle choice tests with CS+ vs. CS- flavors in water and with unflavored sugar vs. water. The KO mice displayed strong preferences (>80%) for the CS+ glucose and CS+ galactose but not for the CS+ fructose flavor. They also preferred glucose and galactose, but not fructose to water. In contrast, the B6 mice preferred all three CS+ flavors to the CS- flavor, and all three sugars to water. In tests with the non-metabolizable sugar α-methyl-d-glucopyranoside (MDG), the KO and B6 mice preferred 8% MDG to water but did not prefer the CS+ 8% MDG to CS-. However, they preferred a CS+ flavor mixed with 4% MDG over the CS- flavor. Trpm5 KO mice also preferred galactose and MDG to fructose in direct choice tests. The Trpm5 KO data indicate that glucose and, to a lesser extent, galactose and MDG have post-oral reinforcing actions that stimulate intake and preference while fructose has a much weaker effect. The CS+ flavor and sugar preferences of B6 mice may be mediated by the sweet taste and/or post-oral actions of the various sugars. Glucose, galactose, and MDG, but not fructose, are ligands for the sodium-glucose transporter 1 (SGLT1) which is implicated in post-oral sugar conditioning in B6 mice.
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Affiliation(s)
- Anthony Sclafani
- Brooklyn College and the Graduate School, City University of New York, Brooklyn, NY 11210, USA.
| | - Karen Ackroff
- Brooklyn College and the Graduate School, City University of New York, Brooklyn, NY 11210, USA
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90
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Morgado-Valle C, Fernandez-Ruiz J, Lopez-Meraz L, Beltran-Parrazal L. Substitution of extracellular Ca2+ by Sr2+ prolongs inspiratory burst in pre-Bötzinger complex inspiratory neurons. J Neurophysiol 2014; 113:1175-83. [PMID: 25429120 DOI: 10.1152/jn.00705.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The pre-Bötzinger complex (preBötC) underlies inspiratory rhythm generation. As a result of network interactions, preBötC neurons burst synchronously to produce rhythmic premotor inspiratory activity. Each inspiratory burst consists of action potentials (APs) on top of a 10- to 20-mV synchronous depolarization lasting 0.3-0.8 s known as inspiratory drive potential. The mechanisms underlying the initiation and termination of the inspiratory burst are unclear, and the role of Ca(2+) is a matter of intense debate. To investigate the role of extracellular Ca(2+) in inspiratory burst initiation and termination, we substituted extracellular Ca(2+) with Sr(2+). We found for the first time an ionic manipulation that significantly interferes with burst termination. In a rhythmically active slice, we current-clamped preBötC neurons (Vm ≅ -60 mV) while recording integrated hypoglossal nerve (∫XIIn) activity as motor output. Substitution of extracellular Ca(2+) with either 1.5 or 2.5 mM Sr(2+) significantly prolonged the duration of inspiratory bursts from 653.4 ± 30.7 ms in control conditions to 981.6 ± 78.5 ms in 1.5 mM Sr(2+) and 2,048.2 ± 448.5 ms in 2.5 mM Sr(2+), with a concomitant increase in decay time and area. Substitution of extracellular Ca(2+) by Sr(2+) is a well-established method to desynchronize neurotransmitter release. Our findings suggest that the increase in inspiratory burst duration is determined by a presynaptic mechanism involving desynchronization of glutamate release within the network.
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Affiliation(s)
- Consuelo Morgado-Valle
- Centro de Investigaciones Cerebrales, Dirección General de Investigaciones, Universidad Veracruzana, Xalapa, Veracruz, Mexico; and
| | - Juan Fernandez-Ruiz
- Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Leonor Lopez-Meraz
- Centro de Investigaciones Cerebrales, Dirección General de Investigaciones, Universidad Veracruzana, Xalapa, Veracruz, Mexico; and
| | - Luis Beltran-Parrazal
- Centro de Investigaciones Cerebrales, Dirección General de Investigaciones, Universidad Veracruzana, Xalapa, Veracruz, Mexico; and
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91
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Medler KF. Calcium signaling in taste cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:2025-32. [PMID: 25450977 DOI: 10.1016/j.bbamcr.2014.11.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 10/21/2014] [Accepted: 11/07/2014] [Indexed: 11/19/2022]
Abstract
The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.
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Affiliation(s)
- Kathryn F Medler
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
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92
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Abstract
TRP channels are expressed in taste buds, nerve fibers, and keratinocytes in the oronasal cavity. These channels play integral roles in transducing chemical stimuli, giving rise to sensations of taste, irritation, warmth, coolness, and pungency. Specifically, TRPM5 acts downstream of taste receptors in the taste transduction pathway. TRPM5 channels convert taste-evoked intracellular Ca(2+) release into membrane depolarization to trigger taste transmitter secretion. PKD2L1 is expressed in acid-sensitive (sour) taste bud cells but is unlikely to be the transducer for sour taste. TRPV1 is a receptor for pungent chemical stimuli such as capsaicin and for several irritants (chemesthesis). It is controversial whether TRPV1 is present in the taste buds and plays a direct role in taste. Instead, TRPV1 is expressed in non-gustatory sensory afferent fibers and in keratinocytes of the oronasal cavity. In many sensory fibers and epithelial cells lining the oronasal cavity, TRPA1 is also co-expressed with TRPV1. As with TRPV1, TRPA1 transduces a wide variety of irritants and, in combination with TRPV1, assures that there is a broad response to noxious chemical stimuli. Other TRP channels, including TRPM8, TRPV3, and TRPV4, play less prominent roles in chemesthesis and no known role in taste, per se. The pungency of foods and beverages is likely highly influenced by the temperature at which they are consumed, their acidity, and, for beverages, their carbonation. All these factors modulate the activity of TRP channels in taste buds and in the oronasal mucosa.
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Affiliation(s)
- Stephen D Roper
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Ave., Miami, FL, 33136, USA,
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93
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Lei YT, Thuault SJ, Launay P, Margolskee RF, Kandel ER, Siegelbaum SA. Differential contribution of TRPM4 and TRPM5 nonselective cation channels to the slow afterdepolarization in mouse prefrontal cortex neurons. Front Cell Neurosci 2014; 8:267. [PMID: 25237295 PMCID: PMC4154465 DOI: 10.3389/fncel.2014.00267] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 08/18/2014] [Indexed: 12/03/2022] Open
Abstract
In certain neurons from different brain regions, a brief burst of action potentials can activate a slow afterdepolarization (sADP) in the presence of muscarinic acetylcholine receptor agonists. The sADP, if suprathreshold, can contribute to persistent non-accommodating firing in some of these neurons. Previous studies have characterized a Ca2+-activated non-selective cation (CAN) current (ICAN) that is thought to underlie the sADP. ICAN depends on muscarinic receptor stimulation and exhibits a dependence on neuronal activity, membrane depolarization and Ca2+-influx similar to that observed for the sADP. Despite the widespread occurrence of sADPs in neurons throughout the brain, the molecular identity of the ion channels underlying these events, as well as ICAN, remains uncertain. Here we used a combination of genetic, pharmacological and electrophysiological approaches to characterize the molecular mechanisms underlying the muscarinic receptor-dependent sADP in layer 5 pyramidal neurons of mouse prefrontal cortex. First, we confirmed that in the presence of the cholinergic agonist carbachol a brief burst of action potentials triggers a prominent sADP in these neurons. Second, we confirmed that this sADP requires activation of a PLC signaling cascade and intracellular calcium signaling. Third, we obtained direct evidence that the transient receptor potential (TRP) melastatin 5 channel (TRPM5), which is thought to function as a CAN channel in non-neural cells, contributes importantly to the sADP in the layer 5 neurons. In contrast, the closely related TRPM4 channel may play only a minor role in the sADP.
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Affiliation(s)
- Ya-Ting Lei
- Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute New York, NY, USA
| | - Sebastien J Thuault
- Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute New York, NY, USA
| | - Pierre Launay
- Equipe Avenir, Institut National de la Santé et de la Recherche Médicale, Service de Néphrologie, Hôpital Bichat, Université Paris Paris, France
| | | | - Eric R Kandel
- Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute New York, NY, USA ; Howard Hughes Medical Institute, Columbia University New York, NY, USA ; Kavli Institute for Brain Sciences, Columbia University New York, NY, USA ; Department of Psychiatry, Columbia University New York, NY, USA
| | - Steven A Siegelbaum
- Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute New York, NY, USA ; Howard Hughes Medical Institute, Columbia University New York, NY, USA ; Kavli Institute for Brain Sciences, Columbia University New York, NY, USA ; Department of Pharmacology, Columbia University New York, NY, USA
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94
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Takahashi H, Rikimaru K, Kiyohara R, Yamaguchi S. Effect of Arachidonic Acid-enriched Oil Diet Supplementation on the Taste of Broiler Meat. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 25:845-51. [PMID: 25049636 PMCID: PMC4093101 DOI: 10.5713/ajas.2011.11517] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 02/21/2012] [Accepted: 02/07/2012] [Indexed: 11/27/2022]
Abstract
To elucidate the relationship between the arachidonic acid (AA) content and the taste of broiler meat, the effects of AA-enriched oil (AAO) supplements on the fatty acid content and sensory perceptions of thigh meat were evaluated. Four types of oil, including corn oil (CO), a 1:1 mixture of AAO and palm oil (PO) (1/2 AAO), a 1:3 mixture of AAO and PO (1/4 AAO), and a 1:7 mixture of AAO and PO (1/8 AAO) were prepared. Each type of oil was mixed with silicate at a ratio of 7:3, and added to the diet at a final proportion of 5% of fresh matter. Broiler chickens were fed these diets for 1 wk before slaughter. In thigh meat, the AA content of the 1/2 and 1/4 AAO groups was significantly higher than that of the CO group. The AA content in thigh meat (y, mg/g) increased linearly with increasing dietary AAO content (x, g/100 g of diet), according to the equation y = 0.5674+0.4596× (r2 = 0.8454). The content of other fatty acids was not significantly different among the 4 diet groups. Sensory evaluation showed that the flavor intensity, umami (L-glutamate taste), kokumi (continuity, mouthfulness, and thickness), and aftertaste of the 1/2 and 1/4 AAO groups were significantly higher than that of the CO group. There were significant positive correlations between AA content in thigh meat and the flavor intensity, total taste intensity, umami, and aftertaste. These data suggest that the taste of broiler meat can be improved by the amount of dietary AA supplementation.
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Affiliation(s)
- H Takahashi
- Livestock Experiment Station, Akita Prefectural Agriculture Forestry and Fisheries Research Center, Daisen 019-1701, Japan
| | - K Rikimaru
- Livestock Experiment Station, Akita Prefectural Agriculture Forestry and Fisheries Research Center, Daisen 019-1701, Japan
| | - R Kiyohara
- Oils and Fats Fundamental Technology Laboratory, J-Oil Mills, Inc., Yokohama 230-0053, Japan
| | - S Yamaguchi
- Oils and Fats Fundamental Technology Laboratory, J-Oil Mills, Inc., Yokohama 230-0053, Japan
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95
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Tordoff MG, Ellis HT, Aleman TR, Downing A, Marambaud P, Foskett JK, Dana RM, McCaughey SA. Salty taste deficits in CALHM1 knockout mice. Chem Senses 2014; 39:515-28. [PMID: 24846212 DOI: 10.1093/chemse/bju020] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Genetic ablation of calcium homeostasis modulator 1 (CALHM1), which releases adenosine triphosphate from Type 2 taste cells, severely compromises the behavioral and electrophysiological responses to tastes detected by G protein-coupled receptors, such as sweet and bitter. However, the contribution of CALHM1 to salty taste perception is less clear. Here, we evaluated several salty taste-related phenotypes of CALHM1 knockout (KO) mice and their wild-type (WT) controls: 1) In a conditioned aversion test, CALHM1 WT and KO mice had similar NaCl avoidance thresholds. 2) In two-bottle choice tests, CALHM1 WT mice showed the classic inverted U-shaped NaCl concentration-preference function but CALHM1 KO mice had a blunted peak response. 3) In brief-access tests, CALHM1 KO mice showed less avoidance than did WT mice of high concentrations of NaCl, KCl, NH(4)Cl, and sodium lactate (NaLac). Amiloride further ameliorated the NaCl avoidance of CALHM1 KO mice, so that lick rates to a mixture of 1000 mM NaCl + 10 µM amiloride were statistically indistinguishable from those to water. 4) Relative to WT mice, CALHM1 KO mice had reduced chorda tympani nerve activity elicited by oral application of NaCl, NaLac, and sucrose but normal responses to HCl and NH(4)Cl. Chorda tympani responses to NaCl and NaLac were amiloride sensitive in WT but not KO mice. These results reinforce others demonstrating that multiple transduction pathways make complex, concentration-dependent contributions to salty taste perception. One of these pathways depends on CALHM1 to detect hypertonic NaCl in the mouth and signal the aversive taste of concentrated salt.
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Affiliation(s)
- Michael G Tordoff
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA,
| | - Hillary T Ellis
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Tiffany R Aleman
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Arnelle Downing
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Philippe Marambaud
- Litwin-Zucker Research Center for the Study of Alzheimer's Disease, Feinstein Institute for Medical Research, 350 Community Drive, Manhasset, NY 11030, USA
| | - J Kevin Foskett
- Department of Physiology, University of Pennsylvania, 415 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Rachel M Dana
- Department of Biology, Cooper Life Sciences Building, CL121, Ball State University, Muncie, IN 47306, USA and
| | - Stuart A McCaughey
- Center for Medical Education, IUSM-Muncie at Ball State University, 221 N. Celia Avenue, MT 201, Muncie, IN 47306, USA
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96
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Abstract
Five canonical tastes, bitter, sweet, umami (amino acid), salty, and sour (acid), are detected by animals as diverse as fruit flies and humans, consistent with a near-universal drive to consume fundamental nutrients and to avoid toxins or other harmful compounds. Surprisingly, despite this strong conservation of basic taste qualities between vertebrates and invertebrates, the receptors and signaling mechanisms that mediate taste in each are highly divergent. The identification over the last two decades of receptors and other molecules that mediate taste has led to stunning advances in our understanding of the basic mechanisms of transduction and coding of information by the gustatory systems of vertebrates and invertebrates. In this Review, we discuss recent advances in taste research, mainly from the fly and mammalian systems, and we highlight principles that are common across species, despite stark differences in receptor types.
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Affiliation(s)
- Emily R Liman
- Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA.
| | - Yali V Zhang
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Craig Montell
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106, USA; Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
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97
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Feng P, Zheng J, Rossiter SJ, Wang D, Zhao H. Massive losses of taste receptor genes in toothed and baleen whales. Genome Biol Evol 2014; 6:1254-65. [PMID: 24803572 PMCID: PMC4079202 DOI: 10.1093/gbe/evu095] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Taste receptor genes are functionally important in animals, with a surprising exception in the bottlenose dolphin, which shows extensive losses of sweet, umami, and bitter taste receptor genes. To examine the generality of taste gene loss, we examined seven toothed whales and five baleen whales and sequenced the complete repertoire of three sweet/umami (T1Rs) and ten bitter (T2Rs) taste receptor genes. We found all amplified T1Rs and T2Rs to be pseudogenes in all 12 whales, with a shared premature stop codon in 10 of the 13 genes, which demonstrated massive losses of taste receptor genes in the common ancestor of whales. Furthermore, we analyzed three genome sequences from two toothed whales and one baleen whale and found that the sour taste marker gene Pkd2l1 is a pseudogene, whereas the candidate salty taste receptor genes are intact and putatively functional. Additionally, we examined three genes that are responsible for taste signal transduction and found the relaxation of functional constraints on taste signaling pathways along the ancestral branch leading to whales. Together, our results strongly suggest extensive losses of sweet, umami, bitter, and sour tastes in whales, and the relaxation of taste function most likely arose in the common ancestor of whales between 36 and 53 Ma. Therefore, whales represent the first animal group to lack four of five primary tastes, probably driven by the marine environment with high concentration of sodium, the feeding behavior of swallowing prey whole, and the dietary switch from plants to meat in the whale ancestor.
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Affiliation(s)
- Ping Feng
- Department of Zoology, College of Life Sciences, Wuhan University, China
| | - Jinsong Zheng
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Stephen J Rossiter
- School of Biological and Chemical Sciences, Queen Mary, University of London, United Kingdom
| | - Ding Wang
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Huabin Zhao
- Department of Zoology, College of Life Sciences, Wuhan University, China
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98
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Transduction for pheromones in the main olfactory epithelium is mediated by the Ca2+ -activated channel TRPM5. J Neurosci 2014; 34:3268-78. [PMID: 24573286 DOI: 10.1523/jneurosci.4903-13.2014] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Growing evidence suggests that the main olfactory epithelium contains a subset of olfactory sensory neurons (OSNs) responding to pheromones. One candidate subpopulation expresses the calcium activated cation channel TRPM5 (transient receptor potential channel M5). Using GFP driven by the TRPM5 promoter in mice, we show that this subpopulation responds to putative pheromones, urine, and major histocompatibility complex peptides, but not to regular odors or a pheromone detected by other species. In addition, this subpopulation of TRPM5-GFP+ OSNs uses novel transduction. In regular OSNs, odorants elicit activation of the cyclic nucleotide-gated (CNG) channel, leading to Ca2+ gating of Cl- channels; in TRPM5-GFP+ OSNs, the Ca2+ -activated Cl- ANO2 (anoctamin 2) channel is not expressed, and pheromones elicit activation of the CNG channel leading to Ca2+ gating of TRPM5. In conclusion, we show that OSNs expressing TRPM5 respond to pheromones, but not to regular odors through the opening of CNG channels leading to Ca2+ gating of TRPM5.
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99
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Fushiki T. Why fat is so preferable: from oral fat detection to inducing reward in the brain. Biosci Biotechnol Biochem 2014; 78:363-9. [DOI: 10.1080/09168451.2014.905186] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Abstract
Potential mechanisms underlying the high palatability of fat can be assessed by reviewing animal studies on fat detection and brain patterns during reward behavior. Fatty acids are likely recognized by receptors on taste buds, with the signals transmitted to the brain through taste nerves. Ingested oil is broken down and absorbed in the gastrointestinal tract, which also sends signals to the brain through unknown mechanisms. Information from both sensory receptors and peripheral tissue is integrated by the brain, resulting in a strong appetite for fatty foods via a reward system. Understanding mechanisms of fat recognition will prove valuable in the development of strategies to manage the high palatability of foods.
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Affiliation(s)
- Tohru Fushiki
- Division of Food Science & Biochemistry, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
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100
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Transduction for pheromones in the main olfactory epithelium is mediated by the Ca2+ -activated channel TRPM5. J Neurosci 2014. [PMID: 24573286 DOI: 10.1523/jneurosci.4903‐13.2014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Growing evidence suggests that the main olfactory epithelium contains a subset of olfactory sensory neurons (OSNs) responding to pheromones. One candidate subpopulation expresses the calcium activated cation channel TRPM5 (transient receptor potential channel M5). Using GFP driven by the TRPM5 promoter in mice, we show that this subpopulation responds to putative pheromones, urine, and major histocompatibility complex peptides, but not to regular odors or a pheromone detected by other species. In addition, this subpopulation of TRPM5-GFP+ OSNs uses novel transduction. In regular OSNs, odorants elicit activation of the cyclic nucleotide-gated (CNG) channel, leading to Ca2+ gating of Cl- channels; in TRPM5-GFP+ OSNs, the Ca2+ -activated Cl- ANO2 (anoctamin 2) channel is not expressed, and pheromones elicit activation of the CNG channel leading to Ca2+ gating of TRPM5. In conclusion, we show that OSNs expressing TRPM5 respond to pheromones, but not to regular odors through the opening of CNG channels leading to Ca2+ gating of TRPM5.
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