Abstract
Humans distinguish between five primary tastes: bitter, sweet, sour, salty and umami. Bitter taste was reported in 2001 to be recognize through G-protein coupled receptors encoded by the T2R family of taste receptor genes. We proposed that sweet and umami taste might also be recognized by T2Rs, and that there is a connection between certain taste disorders and the family of T2R genes. We attempted to compare the gene expression of the T2R family between a group having known taste disorders and a group having normal taste perception. To evaluate clinical qualitative and quantitative taste perception, filter-paper disc (FPD) testing was used. Using in situ hybridization, the T2R16 taste receptor gene was observed between human tongue epithelia of normal subjects and those having disorders. Using Taste Receptor gene Expression Examination (TREE), we PCR-amplified T2R genes as well as the genes having high homology with T2R genes from human tongue epithelium mRNA. We found that T2R16 was expressed in normal subjects, but not expressed in those having disorders. In the normal taste group, some taste receptors were observed by TREE, whereas in the group having disorders, no taste receptor genes were observed. These findings indicated that TREE as well as FPD testing was useful for the assessment of human taste function. We suggested that it is possible to use the T2R genes as the biomarker for evaluating the disorder of the sense of taste. [Jpn J Physiol 55 Suppl:S130 (2005)]
