2005 Fiscal Year Final Research Report Summary
Molecular mechanisms of formation and reformation of taste system for reception and information transmission.
| Project/Area Number |
15209061
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional basic dentistry
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| Research Institution | KYUSHU UNIVERCITY |
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Principal Investigator |
NINOMIYA Yuzo Kyushu University, Graduate School of Dental Sciences, Professor, 大学院歯学研究院, 教授 (50076048)
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| Co-Investigator(Kenkyū-buntansha) |
SHIGEMURA Noriatsu Kyushu University, Graduate School of Dental Sciences, Research associate, 大学院歯学研究院, 助手 (40336079)
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| Project Period (FY) |
2003 – 2005
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| Keywords | taste cell responses / taste nerve fiber responses / taste receptor / gustducin / TRPM5 channels / synapse formation / taste information transmission |
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| Research Abstract |
The purpose of this study is to investigate molecular basis for taste reception and information transmission. To do this, by developing new approaches and improving methods, we examined 1) molecular expression of taste cells whose responses to various taste stimuli were recorded by loose-patch recording configuration, 2) similarities and differences of response profiles of taste cells generating action potentials with taste nerve fibers, and compared 3) responses in wild type and T1r3-KO and TRPM5-KO mice. The results demonstrated that taste cells responding to sweet substances did not always express sweet-response-related molecules, such as T1R3(receptor) and Ggust (G-protein). There was only less than 5% of taste cells responding to sweet substances that expressed synapse-related molecule, SNAP25. More than' 60% of taste cells generating action potentials responded to only one of the four basic taste stimuli and groupings of taste cells based on their best-stimulus and cluster analysis were similar to those of taste nerve fibers. T1R3-KO and TRPM5-KO mice showed residual responses to sweet substances. TRPM5-KO mice lacked temperature sensitivities in response to sweet substances. These results suggest that there probably exist multiple receptor and transduction systems for sweet taste. Taste cells generating action potentials in response to taste stimuli lacked conventional synapses. However, similarity of response profiles between taste cells with action potentials and taste nerve fibers to four basic taste stimuli indicates that taste information from taste cells generating action potentials transmitted to the nerve without major modification. Thereby, they may transmit taste information to the nerve by the pathway other than conventional synapses. TRPM5 channels act as not only channels responsible for transduction for sweet taste but also temperature sensor which produce temperature enhancement of sweet responses.
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