Selective expression of muscarinic acetylcholine receptor subtype M3 by mouse type III taste bud cellsReport as inadecuate




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Pflügers Archiv - European Journal of Physiology

, Volume 468, Issue 11–12, pp 2053–2059

First Online: 14 September 2016Received: 06 September 2016Accepted: 06 September 2016

Abstract

Each taste bud cell TBC type responds to a different taste. Previously, we showed that an unidentified cell types functionally expresses a muscarinic acetylcholine ACh receptor subtype, M3, and we suggested the ACh-dependent modification of its taste responsiveness. In this study, we found that M3 is expressed by type III TBCs, which is the only cell type that possesses synaptic contacts with taste nerve fibers in taste buds. The application of ACh to the basolateral membrane of mouse fungiform TBCs in situ increased the intracellular Ca concentration in 2.4 ± 1.4 cells per taste bud mean ± SD, n = 14. After Ca imaging, we supravitally labeled type II cells phospholipase C β2 PLCβ2-immunoreactive cells with Lucifer yellow CH LY, a fluorescent dye and investigated the positional relationship between ACh-responding cells and LY-labeled cells. After fixation, the TBCs were immunohistostained to investigate the positional relationships between immunohistochemically classified cells and LY-labeled cells. The overlay of the two positional relationships obtained by superimposing the LY-labeled cells showed that all of the ACh-responding cells were type III cells synaptosomal-associated protein 25 SNAP-25-immunoreactive cells. The ACh responses required no added Ca in the bathing solution. The addition of 1 μM U73122, a phospholipase C inhibitor, decreased the magnitude of the ACh response, whereas that of 1 μM U73343, a negative control, had no effect. These results suggest that type III cells respond to ACh and release Ca from intracellular stores. We also discuss the underlying mechanism of the Ca response and the role of M3 in type III cells.

KeywordsCa imaging Fungiform taste bud M3 muscarinic acetylcholine receptor Peeled lingual epithelia Immunohistostaining  Download fulltext PDF



Author: Yusuke Mori - Kohgaku Eguchi - Kiyonori Yoshii - Yoshitaka Ohtubo

Source: https://link.springer.com/







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