Diana Frank2008 Summer Research Fellowship

Principal Investigator: Dr. Marion FrankStudy Coordinator: Dr. Larry Savoy

Introduction Taste Cells

Taste PoreMicrovilliGustatory afferent nerve

Taste MechanismsSalty: Na+ passage through Na+ channelsSour: H+ passage through Na+ channels or

blockage of K+ channelsSweet: G protein-coupled processesBitter: G protein-coupled processes or

blockage of K+ channels

Taste Bud Regions CN VII-Facial Nerve

Fungiform: innervated by the Chorda Tympani (CT) branch

Palate: innervated by the Greater Superficial Petrosal (GSP) branch

CN IX- Glossopharyngeal (GL) NerveFoliate: innervated by the lingual branchCircumvallate Papillae: innervated by the lingual

branch

Diagram of tongue and palate showing regions stimulated in the Spatial Taste Test. (Figure modified from Bartoshuk [1989]).

Circumvallate

PalateFoliate

Fungiform

Taste Study

ChlorhexidineThe active ingredient in the prescription

mouthwash, Peridex*, to treat GingivitusAffects salty and bitter taste qualities and

intensitiesHas a bitter taste

Why is Chlorhexidine’s effect on taste so interesting?

Regional Specificity of Chlorhexidine Effects on Taste

PerceptionGrover and Frank, 2008

Chlorhexidine reduced the intensity of NaCl at fungiform and palatal area stimulation sites (CN VII)

Control intensity ratings were significantly higher at foliate and circumvallate sites (CN IX)

The increased sensitivity of 9th nerve sites could have affected the results

Hypothesis

The decrement in NaCl intensity ratings with CHX rinses would remain larger for CN VII than CN IX regions

The decrement in quinine intensity ratings with CHX rinses would remain equal for CN VII than CN IX regions

Lowering the concentrations for CN IX areas would not produce results different from the Grover et al study

Materials and Methods Subjects: 6 subjects (anticipated), aged 18-

28 Exclusion Criteria: non-smokers, no history

of taste and smell disorders, and in general good health

Consists of a single, 1 hour session Subjects are compensated $8

Materials and Methods 2 training trials to familiarize subjects with

taste stimuli and experience rating intensities using the 0-9 point, fixed interval scaleTraining solutions:

○ 0.1M NaCl (Salty), 0.1M Sucrose (Sweet), 3mM Citric Acid (Sour), Water (Tasteless), and 0.1mM Quinine (Bitter)

1st trial: solution identity given2nd trial: subject identifies and rates solution

intensity

Fixed Interval Scale

Taste Qualities

Data Collection

Materials and Methods

Subject rinses with a rinse and then given a 5 minute break

Subject is given a diagram of the areas of the mouth to be tested (show diagram again)

Materials and Methods Two testing sessions

Test solutions:

1st session: 3 - 5mL water rinses2nd session: 3 - 5mL 1.34 mM CHX rinses

CN VII CN IX

NaCl 1 M 0.32 M

Quinine 1 mM 0.32 mM

Sucrose 1 M 0.32 M

Materials and Methods Each taste stimulus was

sequentially applied to the same areas: fungiform, foliate, circumvallate, and palate

Before each solution was applied, subject was given directions on how to present mouth (by experimenter demonstration)

Preliminary Results

NaCl Quinine Sucrose

Preliminary Results

Related Article Green, B.G. and Schullery, M.T. (2003)

Stimulation of Bitterness by Capsaicin and Menthol: Differences Between Lingual Areas Innervated by the Clossopharyngeal and Chorda Tympani Nerves. Chem. Senses 28: 45-55.

Introduction

Capsaicin is traditionally used to desensitize a class of trigeminal nervesEvokes sensations of heat and acidity-

producing a burning sensation

Menthol is used as an artificial cooling agent

There is minor evidence that capsaicin and methnol may have gustatory properties

Hypothesis

Capsaisin and Menthol would both stimulate taste via different gustatory nerves

Methods and Materials

Results

Results

Conclusions

Capsaicin and menthol produced moderate bitterness in the circumvallate region and weak bitterness in the folliate and fungiform regions

Sensory irritation from Capsaicin was rated significantly higher at the fungiform region

Menthol coolness was rated higher in the circumvallate region

AcknowledgementsMarion Frank

Thomas Hettinger

Larry Savoy

Jonathan Ryder

Kelly O’Neil

Lesley Mancini

Tom Kiely

Kathy Salomone

Lisa Burgio