Journal Article

Expression of Amiloride-sensitive Epithelial Sodium Channels in Mouse Taste Cells after Chorda Tympani Nerve Crush

Noriatsu Shigemura, Abu Ahammad S. Islam, Chiharu Sadamitsu, Ryusuke Yoshida, Keiko Yasumatsu and Yuzo Ninomiya

in Chemical Senses

Volume 30, issue 6, pages 531-538
Published in print July 2005 | ISSN: 0379-864X
Published online July 2005 | e-ISSN: 1464-3553 | DOI: http://dx.doi.org/10.1093/chemse/bji046
Expression of Amiloride-sensitive Epithelial Sodium Channels in Mouse Taste Cells after Chorda Tympani Nerve Crush

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Our previous electrophysiological study demonstrated that amiloride-sensitive (AS) and -insensitive (AI) components of NaCl responses recovered differentially after the mouse chorda tympani (CT) was crushed. AI responses reappeared earlier (at 3 weeks after the nerve crush) than did AS ones (at 4 weeks). This and other results suggested that two salt-responsive systems were differentially and independently reformed after nerve crush. To investigate the molecular mechanisms of formation of the salt responsive systems, we examined expression patterns of three subunits (α, β and γ) of the amiloride-sensitive epithelial Na+ channel (ENaC) in mouse taste cells after CT nerve crush by using in situ hybridization (ISH) analysis. The results showed that all three ENaC subunits, as well as α-gustducin, a marker of differentiated taste cells, were expressed in a subset of taste bud cells from an early stage (1–2 weeks) after nerve crush, although these taste buds were smaller and fewer in number than for control mice. At 3 weeks, the mean number of each ENaC subunit and α-gustducin mRNA-positive cells per taste bud reached the control level. Also, the size of taste buds became similar to those of the control mice at this time. Our previous electrophysiological study demonstrated that at 2 weeks no significant response of the nerve to chemical stimuli was observed. Thus ENaC subunits appear to be expressed prior to the reappearance of AI and AS neural responses after CT nerve crush. These results support the view that differentiation of taste cells into AS or AI cells is initiated prior to synapse formation.

Keywords: amiloride-sensitive epithelial sodium channel; in situ hybridization; nerve crush; taste bud

Journal Article.  5617 words.  Illustrated.

Subjects: Molecular and Cell Biology

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