Glutamate taste: Discrimination between the tastes of glutamate agonists and monosodium glutamate in rats

Eugene R. Delay, G. M. Sewczak, J. R. Stapleton, S. D. Roper

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Taste aversion studies have demonstrated that rats conditioned to avoid monosodium glutamate (MSG) with amiloride added to reduce the intensity of the sodium component of MSG taste, generalize this aversion to aspartic acid and to L-AP4, but not to ionotropic glutamate receptor agonists. That is, MSG, L-AP4 and aspartate have similar tastes to rats. However, conditioned taste aversion methods are unable to show to what extent the tastes of two substances are different. If two substances activate the same afferent processes (e.g. taste receptors), they are likely to produce the same tastes, but if they activate different afferent processes, the subject may detect differences between the tastes of the substances. In this study, rats were tested to determine if they could discriminate between the tastes of these agonists and MSG. We also established the detection thresholds for NMDA, aspartic acid and L-AP4, with and without amiloride (a sodium channel antagonist). Taste threshold values were 1-4 mM for NMDA and aspartic acid and 0.5-2.5 μM for L-AP4. None were affected by 30 μM amiloride. Rats could readily distinguish between the tastes of MSG and NMDA but they had difficulty discriminating between the tastes of aspartic acid and MSG. Rats could also easily distinguish between 10-100 mM MSG and 0.01-5 mM L-AP4. However, in two separate experiments error rates increased significantly when L-AP4 concentrations were between 10-100 mM, indicating that the tastes of L-AP4 and MSG were similar at these concentrations.

Original languageEnglish (US)
Pages (from-to)291-299
Number of pages9
JournalChemical senses
Volume29
Issue number4
DOIs
StatePublished - 2004

Keywords

  • Amiloride
  • Aspartic acid
  • L-AP4
  • Monosodium glutamate
  • NMDA
  • Taste discrimination
  • Taste thresholds

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Food Science
  • Neuroscience(all)
  • Physiology
  • Physiology (medical)
  • Behavioral Neuroscience

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