DOCSLIB.ORG

Morphological and Functional Characterization of the Neurotransmitter Gaba in Adult Rat Taste Buds

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Morphological and Functional Characterization of the Neurotransmitter Gaba in Adult Rat Taste Buds MORPHOLOGICAL AND FUNCTIONAL CHARACTERIZATION OF THE NEUROTRANSMITTER GABA IN ADULT RAT TASTE BUDS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Yu Cao, B.M. * * * * * The Ohio State University 2006 Dissertation Committee: Approved by Professor M. Scott Herness, Adviser ____________________________ Professor Susan P. Travers Adviser Neuroscience Graduate Studies Program Professor Jackie D. Wood ABSTRACT γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system (CNS). By activating the ionotropic GABAA receptor subtype or the metabotropic GABAB receptor subtype, GABA is thought to act as a neurotransmitter or a neuromodulator to exert a wide variety of functions in the CNS including multiple sensory systems. However, little is known regarding involvement of GABA in peripheral gustatory signal processing in the taste buds. GABA is among a broad array of neuroactive substances, which include several neurotransmitters and neuropeptides, identified in mammalian taste buds. The present study is the first to characterize the morphological features, distribution patterns and functional consequences of GABAergic taste receptor cells (TRCs) in adult rat posterior lingual epithelium. Subsets of TRCs were identified as the endogenous source of GABA in taste buds of foliate or circumvallate papillae, as demonstrated by localization of immunoreactivity to both GABA and the GABA synthetic enzyme, glutamate decarboxylase (GAD). Morphologically, GABAergic TRCs resembled other TRCs with known taste signaling functions. Double labeling immunofluorescent studies revealed complex co-expression patterns of GAD with TRC population-specific protein markers (i.e. taste-specific G-protein gustducin α subunit /Gα-gust, neural cell adhesion ii molecule/NCAM and protein gene product 9.5/PGP 9.5), the presynaptic membrane- specific protein marker synaptosomal-associated protein of 25 kDa (SNAP-25) and neuropeptides (i.e. cholecystokinin/CCK and vasoactive intestinal polypeptide/VIP), implying that GABAergic TRCs may have diverse functions in the taste buds. GABA receptor subtypes, GABAA and GABAB, were also localized to subsets of TRCs in rat foliate and circumvallate papillae, indicating that endogenously released GABA may be able to modulate functions of TRCs by activating specific receptors. It appeared that the GABAA receptor α1 subunit, but not the α3 subunit, was present in a group of cells with typical morphological features of TRCs expressing signal transduction molecules, suggesting possible involvement of the GABAA receptor in peripheral gustatory signal processing. The GABAB receptor R1 subunit- immunoreactivity was observed in a group of TRCs separate from the GAD-containing cells in the same bud, arguing a paracrine role for GABA by acting on the GABAB receptor. Interestingly, peptidergic TRCs seemed to receive differentially distributed modulatory input mediated by the GABAB receptor, as suggested by double labeling immunofluorescent studies showing co-localization of the GABAB receptor R1 subunit with the neuropeptide CCK, but not VIP. Possible physiological effects of GABA in the taste buds were examined by patch clamp recordings of TRCs acutely dissociated from rat foliate and circumvallate papillae. GABA and the GABAA receptor-specific agonists, muscimol and isoguvacine, all enhanced isolated chloride currents recorded from TRCs in a dose-dependent manner, consistent with GABAA receptor-mediated actions of GABA reported in the CNS. In addition, GABA and the GABAB receptor-specific agonist baclofen both elicited iii increases of the inwardly rectifying potassium currents (Kir) recorded from TRCs. The enhancing effect on Kir by baclofen could be blocked by the GABAB receptor antagonist CGP 35348 and the G protein blocker GDP-βs, indicating that the G protein-coupled GABAB receptor specifically mediated the effect. Therefore, GABA may modulate different electrical properties of TRC’s by acting on distinctive receptor subtypes. In summary, GABA produced endogenously in the taste buds may modulate functions of various populations of TRCs by acting on specific receptor subtypes. The results of the present study add GABA to a growing list of recently characterized neuroactive substances in the taste buds that includes neurotransmitters and neuropeptides. These neuroactive substances mediating cell-to-cell communication within the taste buds are capable of shaping the final output of chemosensory TRCs and therefore may play important roles in peripheral gustatory signal processing. iv Dedicated to my parents v ACKNOWLEDGMENTS I cannot feel more grateful to my adviser, Dr. Scott Herness, for always being a considerate mentor, for his incredible intellectual support, for his continuing passionate encouragement, and for his great patience throughout the whole process that makes this dissertation to become true. I wish to thank Dr. Fangli Zhao, for never hesitating to share his academic and technical expertise, for his invaluable input into this dissertation, and for his countless helps both inside and outside the laboratory. I also wish to thank Dr. Tiansheng Shen for her pioneering work that forms the base of my dissertation project and for her long-lasting technical support. I am grateful to all current and previous members of the laboratory, especially Dr. Shaogang Lu and Tamara Kolli for their assistance at all times. I appreciate all the kind helps from Dr. Georgia A. Bishop, Barbara Deiner and Dr. James S. King. I am greatly indebted to my husband, Dr. Jinbin Tian, who has been on my side for almost eight happy years. At last, I thank my parents and my twin sister from the bottom of my heart. Without them supporting me unconditionally and helping me taking care of my daughter, this dissertation would not be possible. vi VITA March 24, 1976 ………………………….. Born – Nei Mongol, P.R. China 1994 – 1999 ……………………………… Bachelor of Medicine, Peking University Health Sciences Center. 1999 – present …………………………… Graduate Research Associate, the Ohio State University PUBLICATIONS Research Publication 1. Wang Y, Huang C, Cao Y, Han JS. 1999. Synergistic analgesia between ketamine and clonidine in pain modulation. J Beijing Medical University 2. Wang Y, Huang C, Cao Y, Han JS. 1999. Repeated injection of low dose ketamine for the treatment of acute period of adjuvant arthritic inflammatory pain. Chinese J of Pain Medicine 3. Wang Y, Huang C, Cao Y, Han JS. 2000. Repeated administration of low dose ketamine for the treatment of monoarthritic pain in the rat. Life Sci. Jun 8;67(3):261-7 4. Cao Y, Herness MS. 2001. Localization and functional investigation of CREB in rat taste receptor cells. Soc. Neurosci. Abstr. 27. Program # 287.2 5. Cao Y, Shreffler C, Herness MS. 2002. Localization and functional investigation of the transcription factor CREB in rat taste receptor cells. NeuroReport 13:1321-25 6. Shen T, Kaya N, Zhao FL, Lu SG, Cao Y, and Herness S. 2005. Expression patterns of the neuropeptides VIP and CCK and the transduction molecules α-gustducin and T1R2 in rat taste receptor cells. Neuroscience 130(1): 229-38 7. Herness S, Zhao FL, Kaya N, Shen T, Lu SG, and Cao Y. 2005. Communication routes within the taste bud by neurotransmitters and neuropeptides. Chemical Senses. Jan 30; Suppl 1: i37-8 vii 8. Cao Y, Zhao FL, Herness MS. 2005. GABA as an inhibitory transmitter in the taste bud. Chemical Senses 30:A105-06 9. Zhao FL, Cao Y, Herness MS. 2005. Antagonistic actions of neuropeptides CCK and NPY on rat taste receptor cells. Chemical Senses 30:A101-02 10. Zhao FL, Shen T, Kaya N, Lu SG, Cao Y, Herness S. 2005. Expression, physiological action, and coexpression patterns of neuropeptide Y in rat taste-bud cells. Proc Natl Acad Sci U S A. 102(31):11100-5 11. Wang Y, Zhang Y, Wang W, Cao Y, Han JS. 2005. Effects of synchronous or asynchronous electroacupuncture stimulation with low versus high frequency on spinal opioid release and tail flick nociception. Exp Neurol. 192(1):156-62 12. Cao Y, Zhao FL, Herness MS. 2006. Further characterization of neuropeptides in rat taste receptor cells. Chemical Senses (in press) FIELDS OF STUDY Major Field: Neuroscience viii TABLE OF CONTENTS Page Abstract ……………………………………………………………………………... ii Dedication …………………………………………………………………………... v Acknowledgments …………………………………………………………………... vi Vita ………………………………………………………………………………….. vii List of Tables ………………………………………………………………………... xi List of Figures ……………………………………………………………………….. xii Abbreviation ………………………………………………………………………….. xiv Chapters: 1. Introduction ……………………………………………………………………… 1 1.1. Intrinsic neuromodulation in taste buds …………………………………….. 2 1.2. Communication between TRCs in taste bud ………………………………... 4 1.2.1. Neurotransmitters in TB: 5-HT, NA, glutamate and ATP ………... 6 1.2.2. Neuropeptides in TB: CCK and NPY …………………………….. 9 1.2.3. Other neuroactive substances in TB …………………………….. 10 1.3. GABA as a candidate for mediating neuromodulation in taste bud ………. 11 1.3.1. GABA synthesis ………………………………………………… 11 1.3.2. GABA transporters ……………………………………………… 12 1.3.3. GABA receptors ………………………………………………… 12 1.3.4. GABA in the gustatory system ………………………………….. 15 2. Methods ………………………………………………………………………… 19 2.1. Immunocytochemistry …………………………………………………….. 19 2.1.1. Tissue preparation ……………………………………………….. 19 2.1.2. Conventional immunocytochemistry protocol …………………... 19 2.1.3. TSA-amplified immunocytochemistry protocol ………………… 20 2.1.4. Double-labeling
Load more

Recommended publications
  • Neural Mechanisms of Salt Avoidance in a Freshwater Fish
    Neural Mechanisms of Salt Avoidance in a Freshwater Fish The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Herrera, Kristian J. 2019. Neural Mechanisms of Salt Avoidance in a Freshwater Fish. Doctoral dissertation, Harvard University, Graduate School of Arts & Sciences. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:42029741 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA Neural mechanisms of salt avoidance in a freshwater fish A dissertation presented by Kristian Joseph Herrera to The Department of Molecular and Cellular Biology in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Biology Harvard University Cambridge, Massachusetts April 2019 © 2019 – Kristian Joseph Herrera All rights reserved. Dissertation advisor: Prof. Florian Engert Author: Kristian Joseph Herrera Neural mechanisms of salt avoidance in a freshwater fish Abstract Salts are crucial for life, and many animals will expend significant energy to ensure their proper internal balance. Two features necessary for this endeavor are the ability to sense salts in the external world, and neural circuits ready to execute appropriate behaviors. Most land animals encounter external salt through food, and, in turn, have taste systems that are sensitive to the salt content of ingested material. Fish, on the other hand, extract ions directly from their surrounding environment. As such, they have evolved physiologies that enable them to live in stable ionic equilibrium with their environment.
    [Show full text]
  • Taste and Smell Disorders in Clinical Neurology
    TASTE AND SMELL DISORDERS IN CLINICAL NEUROLOGY OUTLINE A. Anatomy and Physiology of the Taste and Smell System B. Quantifying Chemosensory Disturbances C. Common Neurological and Medical Disorders causing Primary Smell Impairment with Secondary Loss of Food Flavors a. Post Traumatic Anosmia b. Medications (prescribed & over the counter) c. Alcohol Abuse d. Neurodegenerative Disorders e. Multiple Sclerosis f. Migraine g. Chronic Medical Disorders (liver and kidney disease, thyroid deficiency, Diabetes). D. Common Neurological and Medical Disorders Causing a Primary Taste disorder with usually Normal Olfactory Function. a. Medications (prescribed and over the counter), b. Toxins (smoking and Radiation Treatments) c. Chronic medical Disorders ( Liver and Kidney Disease, Hypothyroidism, GERD, Diabetes,) d. Neurological Disorders( Bell’s Palsy, Stroke, MS,) e. Intubation during an emergency or for general anesthesia. E. Abnormal Smells and Tastes (Dysosmia and Dysgeusia): Diagnosis and Treatment F. Morbidity of Smell and Taste Impairment. G. Treatment of Smell and Taste Impairment (Education, Counseling ,Changes in Food Preparation) H. Role of Smell Testing in the Diagnosis of Neurodegenerative Disorders 1 BACKGROUND Disorders of taste and smell play a very important role in many neurological conditions such as; head trauma, facial and trigeminal nerve impairment, and many neurodegenerative disorders such as Alzheimer’s, Parkinson Disorders, Lewy Body Disease and Frontal Temporal Dementia. Impaired smell and taste impairs quality of life such as loss of food enjoyment, weight loss or weight gain, decreased appetite and safety concerns such as inability to smell smoke, gas, spoiled food and one’s body odor. Dysosmia and Dysgeusia are very unpleasant disorders that often accompany smell and taste impairments.
    [Show full text]
  • Chapter 16 Lecture Outline A. Gustation
    Anatomy Lecture Notes Chapter 16 Chapter 16 Lecture Outline A. gustation - gustatory receptor cells are located in organs called taste buds 1. taste buds located in mucosa of mouth and pharynx most are on the sides of fungiform and circumvallate papillae 2. taste buds made of epithelial cells taste pores are openings in the surface of the epithelium gustatory cells - receptor cells supporting cells - separate gustatory cells from each other basal cells - immature cells that replace the other cells 3. gustatory cells have microvilli on apical surface, just inside taste pore membrane covering microvilli contains receptors for sweet, salty, sour, bitter and umami (glutamate) gustatory cells synapse with sensory neurons at base of taste bud Strong/Fall 2008 page 1 Anatomy Lecture Notes Chapter 16 4. gustatory cells activated when molecules dissolved in saliva bind to membrane receptors on microvilli gustatory cell releases neurotransmitter, which initiates action potential in sensory neuron 5. afferent pathways: VII - facial anterior 2/3 of tongue IX - glossopharyngeal posterior 1/3 of tongue X - vagus epiglottis and pharynx sensory neurons terminate in solitary nucleus in medulla oblongata thalamus gustatory cortex B. olfaction - receptors located in olfactory epithelium 1. olfactory epithelium covers superior nasal conchae and superior nasal septum 2. olfactory epithelium contains olfactory cells bipolar neuron receptors supporting cells columnar e. basal cells form new olfactory cells 3. olfactory cells have apical dendrites that project
    [Show full text]
  • Trkb Expression and Dependence Divides Gustatory Neurons Into Three Subpopulations Jennifer Rios-Pilier and Robin F
    Rios-Pilier and Krimm Neural Development (2019) 14:3 https://doi.org/10.1186/s13064-019-0127-z RESEARCHARTICLE Open Access TrkB expression and dependence divides gustatory neurons into three subpopulations Jennifer Rios-Pilier and Robin F. Krimm* Abstract Background: During development, gustatory (taste) neurons likely undergo numerous changes in morphology and expression prior to differentiation into maturity, but little is known this process or the factors that regulate it. Neuron differentiation is likely regulated by a combination of transcription and growth factors. Embryonically, most geniculate neuron development is regulated by the growth factor brain derived neurotrophic factor (BDNF). Postnatally, however, BDNF expression becomes restricted to subpopulations of taste receptor cells with specific functions. We hypothesized that during development, the receptor for BDNF, tropomyosin kinase B receptor (TrkB), may also become developmentally restricted to a subset of taste neurons and could be one factor that is differentially expressed across taste neuron subsets. Methods: We used transgenic mouse models to label both geniculate neurons innervating the oral cavity (Phox2b+), which are primarily taste, from those projecting to the outer ear (auricular neurons) to label TrkB expressing neurons (TrkBGFP). We also compared neuron number, taste bud number, and taste receptor cell types in wild-type animals and conditional TrkB knockouts. Results: Between E15.5-E17.5, TrkB receptor expression becomes restricted to half of the Phox2b + neurons. This TrkB downregulation was specific to oral cavity projecting neurons, since TrkB expression remained constant throughout development in the auricular geniculate neurons (Phox2b-). Conditional TrkB removal from oral sensory neurons (Phox2b+) reduced this population to 92% of control levels, indicating that only 8% of these neurons do not depend on TrkB for survival during development.
    [Show full text]
  • Important Interaction Between Urethral Taste Bud-Like Structures and Onuf's
    +Model ANDROL-280; No. of Pages 10 ARTICLE IN PRESS Revista Internacional de Andrología xxx (xxxx) xxx---xxx www.elsevier.es/andrologia ORIGINAL Important interaction between urethral taste bud-like structures and Onuf’s nucleus following spinal subarachnoid hemorrhage: A hypothesis for the mechanism of dysorgasmia a b,∗ c d Ozgur Caglar , Mehmet Dumlu Aydin , Nazan Aydin , Ali Ahiskalioglu , e f g Ayhan Kanat , Remzi Aslan , Arif Onder a Department of Pediatric Surgery, Medical Faculty of Ataturk University, Erzurum, Turkey b Department of Neurosurgery, Medical Faculty of Ataturk University, Erzurum, Turkey c Department of Psychology, Humanities and Social Sciences Faculty, Uskudar University, Istanbul, Turkey d Department of Anesthesiology, Medical Faculty of Ataturk University, Erzurum, Turkey e Department of Neurosurgery, Medical Faculty of RTE University, Rize, Turkey f Department of Pathology, Medical Faculty of Ataturk University, Erzurum, Turkey g Department of Neurosurgery, Medical Faculty of Inonu University, Malatya, Turkey Received 30 October 2019; accepted 26 May 2020 KEYWORDS Abstract Urethral taste buds; Background: We previously postulated that orgasmic sensation may occur through recently Subarachnoid discovered genital taste bud-like structures. The interaction between the pudendal nerve haemorrhage; and Onuf’s nucleus may be important for developing orgasmic information. The study aims Anorgasmia to investigate whether ischemic damage to Onuf’s nucleus-pudendal network following spinal subarachnoid hemorrhage (SAH) causes taste bud degeneration or not. Methods: The study was conducted on 22 fertile male rabbits who were divided into three 3 groups: control (GI; n = 5), SHAM (GII; n = 5) and study (GIII; n = 12). Isotonic solution, .7 cm , 3 for the SHAM, and .7 cm homologous blood was injected into spinal subarachnoid spaces at S2 level of the study group.
    [Show full text]
  • Nomina Histologica Veterinaria, First Edition
    NOMINA HISTOLOGICA VETERINARIA Submitted by the International Committee on Veterinary Histological Nomenclature (ICVHN) to the World Association of Veterinary Anatomists Published on the website of the World Association of Veterinary Anatomists www.wava-amav.org 2017 CONTENTS Introduction i Principles of term construction in N.H.V. iii Cytologia – Cytology 1 Textus epithelialis – Epithelial tissue 10 Textus connectivus – Connective tissue 13 Sanguis et Lympha – Blood and Lymph 17 Textus muscularis – Muscle tissue 19 Textus nervosus – Nerve tissue 20 Splanchnologia – Viscera 23 Systema digestorium – Digestive system 24 Systema respiratorium – Respiratory system 32 Systema urinarium – Urinary system 35 Organa genitalia masculina – Male genital system 38 Organa genitalia feminina – Female genital system 42 Systema endocrinum – Endocrine system 45 Systema cardiovasculare et lymphaticum [Angiologia] – Cardiovascular and lymphatic system 47 Systema nervosum – Nervous system 52 Receptores sensorii et Organa sensuum – Sensory receptors and Sense organs 58 Integumentum – Integument 64 INTRODUCTION The preparations leading to the publication of the present first edition of the Nomina Histologica Veterinaria has a long history spanning more than 50 years. Under the auspices of the World Association of Veterinary Anatomists (W.A.V.A.), the International Committee on Veterinary Anatomical Nomenclature (I.C.V.A.N.) appointed in Giessen, 1965, a Subcommittee on Histology and Embryology which started a working relation with the Subcommittee on Histology of the former International Anatomical Nomenclature Committee. In Mexico City, 1971, this Subcommittee presented a document entitled Nomina Histologica Veterinaria: A Working Draft as a basis for the continued work of the newly-appointed Subcommittee on Histological Nomenclature. This resulted in the editing of the Nomina Histologica Veterinaria: A Working Draft II (Toulouse, 1974), followed by preparations for publication of a Nomina Histologica Veterinaria.
    [Show full text]
  • Onset of Taste Bud Cell Renewal Starts at Birth and Coincides with a Shift In
    RESEARCH ARTICLE Onset of taste bud cell renewal starts at birth and coincides with a shift in SHH function Erin J Golden1,2, Eric D Larson2,3, Lauren A Shechtman1,2, G Devon Trahan4, Dany Gaillard1,2, Timothy J Fellin1,2, Jennifer K Scott1,2, Kenneth L Jones4, Linda A Barlow1,2* 1Department of Cell & Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, United States; 2The Rocky Mountain Taste and Smell Center, University of Colorado Anschutz Medical Campus, Aurora, United States; 3Department of Otolaryngology, University of Colorado Anschutz Medical Campus, Aurora, United States; 4Department of Pediatrics, Section of Hematology, Oncology, and Bone Marrow Transplant, University of Colorado Anschutz Medical Campus, Aurora, United States Abstract Embryonic taste bud primordia are specified as taste placodes on the tongue surface and differentiate into the first taste receptor cells (TRCs) at birth. Throughout adult life, TRCs are continually regenerated from epithelial progenitors. Sonic hedgehog (SHH) signaling regulates TRC development and renewal, repressing taste fate embryonically, but promoting TRC differentiation in adults. Here, using mouse models, we show TRC renewal initiates at birth and coincides with onset of SHHs pro-taste function. Using transcriptional profiling to explore molecular regulators of renewal, we identified Foxa1 and Foxa2 as potential SHH target genes in lingual progenitors at birth and show that SHH overexpression in vivo alters FoxA1 and FoxA2 expression relevant to taste buds. We further bioinformatically identify genes relevant to cell adhesion and cell *For correspondence: locomotion likely regulated by FOXA1;FOXA2 and show that expression of these candidates is also LINDA.BARLOW@CUANSCHUTZ. altered by forced SHH expression.
    [Show full text]
  • Hypothalamic Fatty Acids and Ketone Bodies Sensing and Role of FAT/CD36 in the Regulation of Food Intake
    Zurich Open Repository and Archive University of Zurich Main Library Strickhofstrasse 39 CH-8057 Zurich www.zora.uzh.ch Year: 2019 Hypothalamic fatty acids and ketone bodies sensing and role of FAT/CD36 in the regulation of food intake Le Foll, Christelle Abstract: The obesity and type-2 diabetes epidemic is escalating and represents one of the costliest biomedical challenges confronting modern society. Moreover, the increasing consumption of high fat food is often correlated with an increase in body mass index. In people predisposed to be obese or already obese, the impaired ability of the brain to monitor and respond to alterations in fatty acid (FA) metabolism is increasingly recognized as playing a role in the pathophysiological development of these disorders. The brain senses and regulates metabolism using highly specialized nutrient-sensing neurons located mainly in the hypothalamus. The same neurons are able to detect variation in the extracellular levels of glucose, FA and ketone bodies as a way to monitor nutrient availability and to alter its own activity. In addition, glial cells such as astrocytes create major connections to neurons and form a tight relationship to closely regulate nutrient uptake and metabolism. This review will examine the different pathways by which neurons are able to detect free fatty acids (FFA) to alter its activity and how high fat diet (HFD)-astrocytes induced ketone bodies production interplays with neuronal FA sensing. The role of HFD-induced inflammation and how FA modulate the reward system will also be investigated here. DOI: https://doi.org/10.3389/fphys.2019.01036 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-175790 Journal Article Published Version The following work is licensed under a Creative Commons: Attribution 4.0 International (CC BY 4.0) License.
    [Show full text]
  • Taste Buds: Cells, Signals and Synapses
    REVIEWS Taste buds: cells, signals and synapses Stephen D. Roper1,2 and Nirupa Chaudhari1,2 Abstract | The past decade has witnessed a consolidation and refinement of the extraordinary progress made in taste research. This Review describes recent advances in our understanding of taste receptors, taste buds, and the connections between taste buds and sensory afferent fibres. The article discusses new findings regarding the cellular mechanisms for detecting tastes, new data on the transmitters involved in taste processing and new studies that address longstanding arguments about taste coding. Taste buds are the peripheral organs of gustation and stimuli are transduced by taste buds. We remind readers are located mainly in the tongue epithelium, although that sweet and bitter, for example, are sensory perceptions; they are also present elsewhere in the oral cavity. They the compounds that elicit them are labelled with these sample the chemical makeup of foods and beverages for same names as a shorthand in this Review, to which purists nutrient content, palatability and potential toxicity. The may object. substantial diversity and redundancy of the molecular receptors for these compounds may reflect the impor­ Sweet. Taste buds detect sugars (probably as an indication tance of identifying nutrients and avoiding chemical of carbohydrates) and other sweet stimuli using diverse threats from the environment. The molecular recogni­ mechanisms. The best­studied receptor for sweet stim­ tion of tastants, which occurs at the apical tips of taste uli is the heterodimer formed of two GPCRs: namely, bud cells, ultimately results in sensory perceptions (for taste receptor type 1 member 2 (T1R2) and T1R3.
    [Show full text]
  • Hedonic Interruption of the Physiological Controls of Eating: Sites and Mechanisms
    Dissertation der Graduate School of Systemic Neurosciences der Ludwig-Maximillians-Universität München Hedonic interruption of the physiological controls of eating: sites and mechanisms ESTE LEIDMAA PhD Thesis 5th of Febuary 2016 Thesis Advisory Committee Professor Osborne Almeida (Supervisor) Professor Christophe Magnan (2nd reviewer) Professor Heidrun Potschka Dr. Susanne E La Fleur (External reviewer) Prof. Harald Luksch (Reviewer from GSN) Date of the thesis defence: 22.06.2016 Pühendusega minu perele Table of Contents Table of Contents ........................................................................................................................... List of Abbreviations ...................................................................................................................... i Abstract ............................................................................................................................................ 5 Chapter 1. General Introduction ...................................................................................................... 7 1.1. Feeding – an essential behaviour .................................................................................... 8 1.1.1. Meeting the energy demands of brain and body ....................................................... 8 1.1.2. Overeating and obesity ............................................................................................. 10 1.1.3. Pathological consequences of obesity .....................................................................
    [Show full text]
  • This Week in the Journal
    The Journal of Neuroscience, October 7, 2020 • 40(41):7779 • 7779 This Week in The Journal Type I Taste Bud Cells NaCl or illuminated water over plain, non- Microglia, like other cell types, release Contribute to Salt Perception illuminated water. vesicles called exosomes, which contain pro- These results indicate that the activation teins and RNA and can be taken up by of Type I taste bud cells leads to activation Caitlin Baumer-Harrison, Martin A. other cells. Because microglial exosomes can of NaCl-responsive neurons in the rNTS contain inflammatory cytokines, Mukherjee Raymond, Thomas A. Myers, Kolbe M. and can drive drink choices in sodium- et al. hypothesized that they are responsible Sussman, Spencer T. Rynberg, et al. depleted mice. This is consistent with the for ethanol-induced neuron death. They hypothesis that ENaCs in Type I cells medi- (see pages 7795–7810) looked specifically at the effects of microglial ate appetitive responses to NaCl. Future exosomes on hypothalamic b -endorphin Taste perception is transduced by receptors work should further test this hypothesis neurons, which are lost when newborn and channels expressed in different types of by determining whether inhibiting Type I (equivalent to human third trimester) rat cells blocks physiological and behavioral taste bud cells. Sweet, umami, and bitter pups are treated with ethanol. Consistent responses to NaCl. tastes are transduced by G-protein-coupled with their hypothesis, markers of microglial receptors expressed in Type II cells, whereas exosomes were higher and their activity was sour taste depends on proton influx into greater in extracellular vesicles isolated from Type III cells.
    [Show full text]
  • Three-Dimensional Ultrastructure of Taste Bud Cells and Nerve Fibers in the Mouse
    Jpn. J. Oral Biol., 27:672-678, 1985. Three-dimensional ultrastructure of taste bud cells and nerve fibers in the mouse Yuko Suzuki and Masako Takeda Department of Oral Anatomy, Higashi-Nippon-Gakuen University, School of Dentistry, Tobetsu, Ishikarigun, Hokkaido 061-02, Japan (Chief: Prof. Masako Takeda) [Accepted for publication : February 6, 1985; Key words: three-demensional ultrastructure / taste bud cell / nerve fiber Abstract: The three-dimensional ultrastructures of the taste bud cells and the nerve fibers in the mouse were investigated by means of electron microscopy using serial ultra-thin sections . Most of the taste bud cells were spindle-shaped and smooth in outline, but a few of type-II cells protruded in cytoplasmic processes from the basal portions. The nerve fibers entering the taste buds through the basal lamina, branched several times, the terminals were formed repeatedly, and then, they narrowed and back to slender, finally ending in the form of a teminal. The number of nerve fibers and terminals which innervate a single taste bud cell differed among the cell types. Each type of cell came in contact with the following per cell , type- I and basal cells with 1-2 nerve fibers, type- II cells with 1-4 nerve fibers, and type-DI (gustatory) cells with 2-4 nerve fibers. The number of nerve terminals in contact with each type of cell was 1-2 per cell in type- I and basal cells, 2-4 type-il and 3-6 in type-III. The nerve fibers which came in contact with type-III cells always formed several (mean number of 8 per cell) afferent synapses.
    [Show full text]