Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA306

Poster Communications

CD36 polymorphism (rs1761667) and PROP taster status affect the bioelectrical response to oleic acid by electrophysiological recording from the human tongue.

G. Sollai1, M. Melis1, D. Pani2, P. Cosseddu2, A. Bonfiglio2, B. Tepper3, R. Crnjar1, I. Tomassini Barbarossa1

1. Dept. of Biomedical Sciences, University of Cagliari, Monserrato, CA, Italy. 2. Dept. of Electrical and Electronic Engineering, University of Cagliari, Monserrato, CA, Italy. 3. Dept. of Food Science, Rutgers University, New Brunswick, New Jersey, United States.

Oro-sensory perception of dietary fat varies among individuals, thus influencing nutritional status. Several studies showed that fat detection and preferences are associated with common variants in the gene coding for CD36 scavenger receptor which facilitates fatty acid uptake and oxidation. In addition, it is known that non-taster individuals for the oral marker, 6-n-propylthiouracil (PROP), are less responsive to fats and have a lower ability to detect them in foods. However, the role of the PROP phenotype in fat perception is controversial. These divergent conclusions may be due to the fact that sensory analyses are carried out by psychophysical approaches and rely on highly subjective evaluations. Here we present data about direct measures of the degree of activation of the peripheral gustatory system in response to taste stimulation, obtained by electrophysiological recordings from the tongue, in 35 subjects classified by PROP taster status. All were genotyped for TAS2R38 gene. The PAV haplotype of TAS2R38 has a high affinity for PROP, and the G allele of CD36 polymorphism (rs1761667), is characterized by an increased protein expression. The biopotentials generated by taste stimulation with oleic acid were recorded by means of differential electrophysiological derivations between two silver electrodes, one in contact with the ventral surface of the tongue and one in perfect adhesion with the dorsal surface. The signals (electrotastegrams, ETGs) were recorded by a polygraph for human use, visualized in real time on a PC and analyzed by Clampfit 10.0 software. The amplitude values were determined at 2.5, 5, 10 and 15 s, and the depolarization rate (mV/s) calculated at the same time points. Oleic acid stimulation evoked positive monophasic potentials characterized by a faster initial rise followed by a slower phase. These deviations, represent a measure of the summated voltage change resulting from the response of stimulated taste cells. In addition, repeated measures ANOVA revealed that the time course of the depolarization amplitude, as well as depolarization rate, were associated with PROP tasting and CD36. The depolarization amplitude increased during stimulation in PROP tasters and in subjects having at least 1 PAV haplotype in TAS2R38 or G allele in CD36, but did not change in non-tasters and in subjects homozygous for the non-tasting form in both genes. In conclusion, we showed that the waveform of bioelectrical signals in response to oleic acid depends on PROP taster status and genotype of TAS2R38 and rs1761667 polymorphism of CD36. Our results provide the first objective data on a direct physiological relationship between the oro-sensory perception of fats and variation in these genes.

Where applicable, experiments conform with Society ethical requirements