The taste of monosodium glutamate: Membrane receptors in taste buds

Nirupa Chaudhari, Hui Yang, Cynthia Lamp, Eugene Delay, Claire Cartford, Trang Than, Stephen Roper

Research output: Contribution to journalArticle

210 Scopus citations

Abstract

Receptor proteins for photoreception have been studied for several decades. More recently, putative receptors for olfaction have been isolated and characterized. In contrast, no receptors for taste have been identified yet by molecular cloning. This report describes experiments aimed at identifying a receptor responsible for the taste of monosodium glutamate (MSG). Using reverse transcriptase (RT)-PCR, we found that several ionotropic glutamate receptors are present in rat lingual tissues. However, these receptors also could be detected in lingual tissue devoid of taste buds. On the other hand, RT-PCR and RNase protection assays indicated that a G- protein-coupled metabotropic glutamate receptor, mGluR4, also is expressed in lingual tissues and is limited only to taste buds. In situ hybridization demonstrated that mGluR4 is detectable in 40-70% of vallate and foliate taste buds but not in surrounding nonsensory epithelium, confirming the localization of this metabotropic receptor to gustatory cells. Expression of mGluR4 in taste buds is higher in preweaning rats compared with adult rats. This may correspond to the known higher sensitivity to the taste of MSG in juvenile rodents. Finally, behavioral studies have indicated that MSG and L- 2-amino-4-phosphonobutyrate (L-AP4), a ligand for mGluR4, elicit similar tastes in rats. We conclude that mGluR4 may be a chemosensory receptor responsible, in part, for the taste of MSG.

Original languageEnglish (US)
Pages (from-to)3817-3826
Number of pages10
JournalJournal of Neuroscience
Volume16
Issue number12
DOIs
StatePublished - 1996

Keywords

  • chemosensory
  • glutamate receptors
  • gustation
  • rats
  • taste buds
  • umami

ASJC Scopus subject areas

  • Neuroscience(all)

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