 |
||||
|
||||
|
||||
|
||||
|
||||
Previous Article | Next Article
The Journal of Neuroscience, March 1, 2002, 22(5):1937-1941
Rats Fail to Discriminate Quinine from Denatonium: Implications for the Neural Coding of Bitter-Tasting Compounds
Alan C. Spector and Stacy L. Kopka Department of Psychology, University of Florida, Gainesville, Florida 32611
Recent molecular findings indicate that many different G-protein-coupled taste receptors that bind with "bitter-tasting" ligands are coexpressed in single taste receptor cells in taste buds, leading to the prediction that mammals can respond behaviorally to structurally diverse "bitter" tastants but cannot discriminate among them. However, recent in situ calcium-imaging findings imply that rat taste receptor cells are more narrowly tuned to respond to bitter-tasting compounds than had been predicted from molecular findings, suggesting that these animals can discriminate among these chemicals. Using an operant conditioning paradigm, we demonstrated that rats cannot discriminate between two structurally dissimilar bitter compounds, quinine hydrochloride and denatonium benzoate, despite the fact that these tastants are thought to stimulate different taste receptor cells. These rats were nonetheless able to show concentration-dependent avoidance responses to both compounds in brief-access tests and to discriminate among other taste stimuli, including quinine versus KCl, denatonium versus KCl, and NaCl versus KCl. Importantly, the concentrations were varied in the discrimination tests to render intensity an irrelevant cue. We conclude that denatonium and quinine produce a unitary taste sensation, leaving open the likely possibility that other compounds fall into this class. Although a broader array of compounds needs to be tested, our findings lend support to the hypothesis that there is only one qualitative type of bitterness. These results also highlight the need to confirm predictions about the downstream properties of the gustatory system, or any sensory system, based on upstream molecular and biophysical events.
Key words: bitter taste; bitter discrimination; rat; psychophysics; quinine hydrochloride; denatonium benzoate; T2R receptor family; gustatory system
Copyright © 2002 Society for Neuroscience 0270-6474/02/2251937-05$05.00/0
This article has been cited by other articles:
L. C. Geran and S. P. Travers
Bitter-Responsive Gustatory Neurons in the Rat Parabrachial Nucleus
J Neurophysiol, March 1, 2009; 101(3): 1598 - 1612.
[Abstract] [Full Text] [PDF]
J. I. Glendinning
How Do Predators Cope With Chemically Defended Foods?
Biol. Bull., December 1, 2007; 213(3): 252 - 266.
[Abstract] [Full Text] [PDF]
M. Behrens, S. Foerster, F. Staehler, J.-D. Raguse, and W. Meyerhof
Gustatory Expression Pattern of the Human TAS2R Bitter Receptor Gene Family Reveals a Heterogenous Population of Bitter Responsive Taste Receptor Cells
J. Neurosci., November 14, 2007; 27(46): 12630 - 12640.
[Abstract] [Full Text] [PDF]
C. D. Dotson and A. C. Spector
Behavioral Discrimination between Sucrose and Other Natural Sweeteners in Mice: Implications for the Neural Coding of T1R Ligands
J. Neurosci., October 17, 2007; 27(42): 11242 - 11253.
[Abstract] [Full Text] [PDF]
L. C. Geran and S. P. Travers
Single Neurons in the Nucleus of the Solitary Tract Respond Selectively to Bitter Taste Stimuli
J Neurophysiol, November 1, 2006; 96(5): 2513 - 2527.
[Abstract] [Full Text] [PDF]
C. H. Lemon and D. V. Smith
Neural Representation of Bitter Taste in the Nucleus of the Solitary Tract
J Neurophysiol, December 1, 2005; 94(6): 3719 - 3729.
[Abstract] [Full Text] [PDF]
S. M. Brasser, K. Mozhui, and D. V. Smith
Differential Covariation in Taste Responsiveness to Bitter Stimuli in Rats
Chem Senses, November 1, 2005; 30(9): 793 - 799.
[Abstract] [Full Text] [PDF]
A. C. Spector and S. P. Travers
The representation of taste quality in the Mammalian nervous system.
Behav Cogn Neurosci Rev, September 1, 2005; 4(3): 143 - 191.
[Abstract] [PDF]
C.Y. Chan, J.E. Yoo, and S.P. Travers
Diverse Bitter Stimuli Elicit Highly Similar Patterns of Fos-like Immunoreactivity in the Nucleus of the Solitary Tract
Chem Senses, September 1, 2004; 29(7): 573 - 581.
[Abstract] [Full Text] [PDF]
C. H. Lemon, S. M. Brasser, and D. V. Smith
Alcohol Activates a Sucrose-Responsive Gustatory Neural Pathway
J Neurophysiol, July 1, 2004; 92(1): 536 - 544.
[Abstract] [Full Text] [PDF]
T. M. Nelson, S. D. Munger, and J. D. Boughter Jr
Taste Sensitivities to PROP and PTC Vary Independently in Mice
Chem Senses, October 1, 2003; 28(8): 695 - 704.
[Abstract] [Full Text] [PDF]
J. I. Glendinning, A. Davis, and S. Ramaswamy
Contribution of Different Taste Cells and Signaling Pathways to the Discrimination of "Bitter" Taste Stimuli by an Insect
J. Neurosci., August 15, 2002; 22(16): 7281 - 7287.
[Abstract] [Full Text] [PDF]
|
|
|
|
 |
|