Glutamate Taste: Discrimination between the Tastes of Glutamate Agonists and Monosodium Glutamate in Rats

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, MS...

Full description

Saved in:
Bibliographic Details
Published inChemical senses Vol. 29; no. 4; pp. 291 - 299
Main Authors Delay, E.R., Sewczak, G.M., Stapleton, J.R., Roper, S.D.
Format Journal Article
LanguageEnglish
Published Oxford Oxford University Press 01.05.2004
Oxford Publishing Limited (England)
Subjects
Online AccessGet full text

Cover

Loading…
More Information
Summary: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.
Bibliography:local:bjh031
istex:9775A7D5E34F74A0CB0C028DE2D90D6C1B163318
ark:/67375/HXZ-CDV1TSX9-2
Correspondence to be sent to: Eugene R. Delay, Neuroscience Program, Department of Psychology, Regis University, 3333 Regis Blvd, Denver, Colorado, 80221, USA. e-mail: edelay@regis.edu
ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ObjectType-Article-1
ObjectType-Feature-2
ISSN:0379-864X
1464-3553
1464-3553
DOI:10.1093/chemse/bjh031