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Functional expression of ionotropic purinergic receptors on mouse taste bud cells

By Ryotaro Hayato, Yoshitaka Ohtubo and Kiyonori Yoshii

Abstract

Neurotransmitter receptors on taste bud cells (TBCs) and taste nerve fibres are likely to contribute to taste transduction by mediating the interaction among TBCs and that between TBCs and taste nerve fibres. We investigated the functional expression of P2 receptor subtypes on TBCs of mouse fungiform papillae. Electrophysiological studies showed that 100 μm ATP applied to their basolateral membranes either depolarized or hyperpolarized a few cells per taste bud. Ca2+ imaging showed that similarly applied 1 μm ATP, 30 μm BzATP (a P2X7 agonist), or 1 μm 2MeSATP (a P2Y1 and P2Y11 agonist) increased intracellular Ca2+ concentration, but 100 μm UTP (a P2Y2 and P2Y4 agonist) and α,β-meATP (a P2X agonist except for P2X2, P2X4 and P2X7) did not. RT-PCR suggested the expression of P2X2, P2X4, P2X7, P2Y1, P2Y13 and P2Y14 among the seven P2X subtypes and seven P2Y subtypes examined. Immunohistostaining confirmed the expression of P2X2. The exposure of the basolateral membranes to 3 mm ATP for 30 min caused the uptake of Lucifer Yellow CH in a few TBCs per taste bud. This was antagonized by 100 μm PPADS (a non-selective P2 blocker) and 1 μm KN-62 (a P2X7 blocker). These results showed for the first time the functional expression of P2X2 and P2X7 on TBCs. The roles of P2 receptor subtypes in the taste transduction, and the renewal of TBCs, are discussed

Topics: Neuroscience
Publisher: Blackwell Publishing Ltd
OAI identifier: oai:pubmedcentral.nih.gov:2277161
Provided by: PubMed Central
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