First objective evaluation of taste sensitivity to 6-n-propylthiouracil (PROP), a paradigm gustatory stimulus in humans

Giorgia Sollai,Melania Melis,Ilenia Usai,Piero Cosseddu,Danilo Pani,Iole Tomassini Barbarossa,Roberto Crnjar,Annalisa Bonfiglio

doi:10.1038/srep40353

Abstract

Practical and reliable methods for the objective measure of taste function are critically important for studying eating behavior and taste function impairment. Here, we present direct measures of human gustatory response to a prototypical bitter compound, 6-n-propyltiouracil (PROP), obtained by electrophysiological recordings from the tongue of subjects who were classified for taster status and genotyped for the specific receptor gene (TAS2R38), and in which taste papilla density was determined. PROP stimulation evoked negative slow potentials that represent the summated depolarization of taste cells. Depolarization amplitude and rate were correlated with papilla density and perceived bitterness, and associated with taster status and TAS2R38. Our study provides a robust and generalizable research tool for the quantitative measure of peripheral taste function, which can greatly help to resolve controversial outcomes on the PROP phenotype role in taste perception and food preferences, and be potentially useful for evaluating nutritional status and health.

Highlights

Taste acts as a final checkpoint for food acceptance or rejection behavior and enables individuals to distinguish nutrient-rich food from noxious substances[1,2]
Density of fungiform papillae varied with PROP taster status or TAS2R38 polymorphisms (F2,40 = 29.447; P < 0.00001 or F2,40 = 8.842; P = 0.0007) (Fig. 2)
We found that ETG, used as a direct measure of the peripheral taste function in humans, is a highly reliable and yet moderately non-invasive method that allows us to obtain objective and quantitative data which are not affected by the individual’s subjective confounding factors

Summary

Introduction

Taste acts as a final checkpoint for food acceptance or rejection behavior and enables individuals to distinguish nutrient-rich food from noxious substances[1,2]. This partly depends on social and cultural factors, but there is an important genetic component[4] Within this nutritional context, PROP tasting, which is a common genetic trait present in all population groups across the globe[5], has gained, in the last decades, considerable attention as a paradigm of general taste perception and as an oral marker for food preferences and eating habits that impacts on nutritional status and health[3]. To evaluate activation at the central level, these studies use the functional Magnetic Resonance (f MR) which cannot be practically applied to large numbers of subjects[29,30] Based on these considerations, it would be of great interest to design and validate a practical and reliable method to measure human taste responses objectively and non-invasively on a large population sample. We compare two parameters (voltage amplitude and depolarization rate) describing the waveform of ETGs with the intensity of perceived PROP bitterness, PROP taster status, TAS2R38 genotypes, and the density of fungiform papillae of subjects

Methods

Results

Conclusion