Abstract
The effect of unsaturated fatty acids on taste sensitivity was explored by human psychophysical study, molecular biological study and mouse neuroethological study. Inhibitory effects of fatty acids on bitter taste including QHCl and denatonium were demonstrated in perceived taste intensity test in human, the mouse behavioral experiment using a short -term lick test (10 sec) and responses in the chorda tympani (CT) and the glossopharyngeal (GL) nerve in wild type mice. In contrast, fatty acids have no effect on bitter tasting L-amino acids, NaCl, HCl, sucrose and MSG in all study performed. To investigate involvement of Ggustducin in this inhibitory effect of fatty acids, nerve recording from gustducin KO mice and in vitro G-protein activation assay using bovine taste membrane were employed. Results from gustducin KO mice showed no suppression in bitter taste responses both in the CT and the GL. In vitro G-protein activation assay using bovine taste membrane showed that the activation of both gustducin and transducin by denatonium was significantly inhibited by DHA and oleic acid, and that the activation of transducin by rhodopsin was not inhibited. These results suggest that fatty acids specifically inhibit responses to bitter stimuli by suppression of activation of T2R receptors which coupled with Ggustducin and Gtransducin. [J Physiol Sci. 2006;56 Suppl:S90]
