Electrophysiological and behavioral studies on the taste of umami substances in the rat

Yamamoto, Takashi; Matsuo, Ryuji; Fujimoto, Yoshiyuki; Fukunaga, Isao; Miyasaka, Akiko; Imoto, Toshiaki

doi:10.1016/0031-9384(91)90204-2

Cited by 111 publications

(84 citation statements)

References 19 publications

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“…Nonetheless, the binding affinity of glutamate at taste receptors is in the same range as taste thresholds for glutamate (l-10 mM in rats) (Yamamoto et al, 1991). This implies that GluRs in taste buds may possess ligand-binding sites different from those of synaptic receptors.…”

Section: Discussionmentioning

confidence: 97%

“…We are in the process of obtaining and analyzing full-length cDNA clones to examine this question. The binding of glutamate to taste receptors as well as the perceived taste of MSG is potentiated by 5'-IMP and 5'-GMP Chaudhari et al l Membrane Receptors in Taste Buds (Sato and Akaike, 1965;Torii and Cagan, 1980;Yamamoto et al, 1991). The primary sequence of the extracellular N terminus of brain mGluR4 does not contain consensus nucleotide-binding motifs.…”

Section: Discussionmentioning

confidence: 99%

“…All solutions of glutamate agonists were titrated to pH 6.0-7.0 to avoid potential complications introduced by acid taste. Also, all solutions, including water, contained 30 pM amiloride to minimize the contribution of Na+ taste (Heck et al, 1984;Yamamoto et al, 1991;Gilbertson and Gilbertson, 1994). Half of the rats for each taste stimulus were injected intraperitoneally with 0.3 M LiCl (at 1 ml/100 gm body weight).…”

Section: Methodsmentioning

confidence: 99%

“…We also tested rats with 100 mM sucrose, because MSG aversion is known to generalize to sucrose in the presence of amiloride (Yamamoto et al, 1991). This control was included to validate the conditioning paradigm in the event that none of the agonists had shown any generalization.…”

Section: Methodsmentioning

confidence: 99%

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The Taste of Monosodium Glutamate: Membrane Receptors in Taste Buds

et al. 1996

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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 (IV)-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.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

The Taste of Monosodium Glutamate: Membrane Receptors in Taste Buds

et al. 1996

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“…The depressing effect of GA on the sweet taste sensation in human has been known for a long time [20][21][22][23][24][25][26] . The inhibitory effects of GA, a mixture of triterpene glucuronides, from the plant -Gymnema sylvestre, on the glucose absorption in the small intestine and the improvement of glucose tolerance have been noticed since the 1980s [15,16,27,28] .…”

Section: Discussionmentioning

confidence: 99%