| 研究実績の概要 |
Expressions of fatty acid receptors (Ffar) 1, 2, 3, and 4 (Ffar1: middle to long-chain, Ffars2 and 3: short-chains, and Ffar4: middle-chain fatty acid receptor, respectively) were observed along the time course of the ontogenetic development using Wistar rats. Taste buds of circumvallate, foliate, and fungiform papillae were obtained along the time course of the ontogenetic development, from fetal, neonatal, postnatal to adult stages. Fetuses ingest amniotic fluid, neonates take milk, and adults take pellets. We examined the changes in Ffars with the changes in the diets. The amounts of messenger RNAs were measured by real-time PCR using Taqman probes. Beta actin was measured simultaneously as a house-keeping gene. The localization of these fatty acid receptors was investigated by immunohistochemistry. The Kitasato University Animal Rights Committee preliminarily approved all the procedures.
The immunohistochemical observations revealed that these receptors were localized in the taste cells of all papillae examined. Also, the mRNAs of the fatty acid receptors were expressed in the taste buds throughout the fetal to adult stages.
These results suggest that taste buds play essential roles in perceiving fat sensation. Sweet, bitter, sour, and umami (savory) taste have been indicated as fundamental taste elements so far. The present study suggests that fat taste is a candidate as the 6th taste sensation. Since the expression of fatty acid receptors was demonstrated from the early stages of the development, this sensation must play some significant roles for the rats.
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