Umami taste in mice uses multiple receptors and transduction pathways

Keiko Yasumatsu, Yoko Ogiwara, Shingo Takai, Ryusuke Yoshida, Ken Iwatsuki, Kunio Torii, Robert F. Margolskee, Yuzo Ninomiya

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56 Citations (Scopus)

Abstract

The distinctive umami taste elicited by l-glutamate and some other amino acids is thought to be initiated by G-protein-coupled receptors. Proposed umami receptors include heteromers of taste receptor type 1, members 1 and 3 (T1R1+T1R3), and metabotropic glutamate receptors 1 and 4 (mGluR1 and mGluR4). Multiple lines of evidence support the involvement of T1R1+T1R3 in umami responses of mice. Although several studies suggest the involvement of receptors other than T1R1+T1R3 in umami, the identity of those receptors remains unclear. Here, we examined taste responsiveness of umami-sensitive chorda tympani nerve fibres from wild-type mice and mice genetically lacking T1R3 or its downstream transduction molecule, the ion channel TRPM5. Our results indicate that single umami-sensitive fibres in wild-type mice fall into two major groups: sucrose-best (S-type) and monopotassium glutamate (MPG)-best (M-type). Each fibre type has two subtypes; one shows synergism between MPG and inosine monophosphate (S1, M1) and the other shows no synergism (S2, M2). In both T1R3 and TRPM5 null mice, S1-type fibres were absent, whereas S2-, M1- and M2-types remained. Lingual application of mGluR antagonists selectively suppressed MPG responses of M1- and M2-type fibres. These data suggest the existence of multiple receptors and transduction pathways for umami responses in mice. Information initiated from T1R3-containing receptors may be mediated by a transduction pathway including TRPM5 and conveyed by sweet-best fibres, whereas umami information from mGluRs may be mediated by TRPM5-independent pathway(s) and conveyed by glutamate-best fibres.

Original languageEnglish
Pages (from-to)1155-1170
Number of pages16
JournalJournal of Physiology
Volume590
Issue number5
DOIs
Publication statusPublished - Feb 1 2012

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ASJC Scopus subject areas

  • Physiology

Cite this

Yasumatsu, K., Ogiwara, Y., Takai, S., Yoshida, R., Iwatsuki, K., Torii, K., Margolskee, R. F., & Ninomiya, Y. (2012). Umami taste in mice uses multiple receptors and transduction pathways. Journal of Physiology, 590(5), 1155-1170. https://doi.org/10.1113/jphysiol.2011.211920