抄録
Recent molecular biological studies revealed many molecules concerned in taste reception. However, there is little evidence for direct involvement of these molecules at the cellular level. Here, we investigated taste responses of receptor cells generating action potentials and mRNA expression of taste related genes in these cells at the same time. Using loose patch technique, we recorded taste responses of receptor cells of mouse fungiform papillae. Two types of NaCl responding cells exist: one is amiloride-sensitive and the other amiloride-insensitive. In some cells, responses to MSG were enhanced when MSG was mixed with IMP. Responses to sweet substances in some cells were suppressed by apical treatment of gurmarin and recovered after apical application of β-cyclodextrin. About 60% of taste cells responded to one of four taste stimuli tested and the entropy value presenting the breadth of responsiveness was 0.207 ± 0.253, which was close to that for the nerve fibers. These results suggest that taste cells generating action potentials have response characteristics to taste stimuli that are comparable to those for nerve fibers. At the end of recording, the cell was withdrawn from a taste bud and examined mRNA expression of taste related genes by RT-PCR. Our preliminary data indicate that a taste cell responding to sweet stimuli expressed T1R3 and α-gustducin mRNA. Thus, this technique might be useful to examine molecular expression in receptor cells responding to taste stimuli. [Jpn J Physiol 54 Suppl:S175 (2004)]
