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Effect of cigarette smoke and nicotine on taste processing

Institution: University of California, Davis
Investigator(s): Christopher Simons, Ph.D.
Award Cycle: 2002 (Cycle 11) Grant #: 11FT-0101 Award: $70,000
Subject Area: Nicotine Dependence
Award Type: Postdoctoral Fellowship Awards
Abstracts

Initial Award Abstract
Tobacco use is often associated with weight loss. We believe that smoking and nicotine change the way foods taste making them less palatable so smokers lose weight. We will test this hypothesis by recording electrical activity in rat taste nerve cells and by studying human taste perception. We have evidence that nicotine strongly suppresses nerve activity in brain regions involved in taste sensation. Several properties of nicotine may cause this suppression: (a) nicotine’s bitter taste may suppress other tastes; (b) the irritant sensation of nicotine might inhibit taste responses similar to the way capsaicin (the chemical that makes chili peppers burn) reduces some tastes; (c) nicotine can enter the brain where it could activate areas involved in feeding. Feeding centers interact with brain areas involved in taste so that activating them may inhibit nerve cells responsive to tastants. A major goal of this proposal, therefore, is to confirm the ability of nicotine to suppress other tastes and to investigate the underlying mechanisms.

Taste Suppression: We will record electrical activity in brain nerve cells responsive to tastants before and after nicotine, quinine (which tastes bitter) or cigarette smoke is applied to the tongue. We will compare the effect of nicotine and quinine on nerve cell activity caused by taste stimuli so we can differentiate between bitter- or pain-induced mechanisms of taste suppression. We will also test cigarette smoke to determine if other smoke constituents besides nicotine might contribute to taste suppression. To determine whether nicotine-suppression of taste occurs in the tongue or in the brain, we will use chemicals that selectively activate or block the nerve cell receptors normally responsive to nicotine. These chemicals cannot get into the brain, therefore, an effect of these chemicals on nicotine-induced taste suppression would suggest that the site of nicotine suppression is the tongue. We will also study how nicotine affects taste in human subjects, for comparison with the neural data. We have developed a sensitive method to determine if nicotine reduces the perceived intensity of model tastes and real foods. Moreover, because previous studies on taste threshold unknowingly introduced bias making the results suspect, we will re-address the role of nicotine in raising taste thresholds using a bias-free paradigm that has proven very useful in taste threshold experiments.

Palatability: Alterations in palatability following smoking will be studied. We will first test if reductions in perceived taste intensity result in loss of palatability by having subjects rate the palatability of various foods following blockade of sweet taste. Second, smoking subjects will be asked to abstain briefly (2 hrs) and give palatability ratings to various foods. These ratings will be compared to those obtained one week later, when subjects return to re-evaluate the palatability of the same foods immediately following a smoking bout. Finally, subjects newly enrolled in a smoking cessation program will rate food palatability during the time in which they are smoking. Subjects successfully completing their cessation program, will be asked to return to the laboratory and re-evaluate the palatability of previously tested food items.

Taste cell expression of nicotine receptors: Finally, molecular biology techniques will be used to determine whether nicotine receptors are found on taste cells in the tongue. Identification of these receptors would provide a novel mechanism by which bitter chemicals could activate taste cells.
Publications

Activation of brain stem neurons by irritant stimulation of the throat assessed by c-fos immunohistochemistry.
Periodical: Experimental Brain Research Index Medicus:
Authors: Boucher Y, Simons CT, Cuellar JM, Jung SW, Carstens MI, Carstens E ART
Yr: 2003 Vol: 148 Nbr: Abs: Pg: 211-218

Suppression of central taste transmission by oral capsaicin.
Periodical: Journal of Neuroscience Index Medicus:
Authors: Simons CT, Boucher Y, Carstens E ART
Yr: 2003 Vol: 23 Nbr: Abs: Pg: 978-985

Trigeminal modulation of gustatory neurons in the NTS.
Periodical: Brain Research Index Medicus:
Authors: Boucher Y, Simons CT, Faurion A, Azerad J, Carstens E ART
Yr: 2003 Vol: 973 Nbr: Abs: Pg: 265-274

Activation of neurons in trigeminal caudalis by noxious oral acidic or salt stimuli is not reduced by amiloride.
Periodical: Brain Research Index Medicus:
Authors: Sudo S, Sudo M, Simons CT, Dessirier JM, Carstens MI, Carstens E ART
Yr: 2003 Vol: 969 Nbr: Abs: Pg: 237-243

Lack of quinine-evoked activity in rat trigeminal subnucleus caudalis.
Periodical: Chemical Senses Index Medicus:
Authors: Simons CT, Boucher Y, Carstens E ART
Yr: 2003 Vol: 28 Nbr: Abs: Pg: 253-259

Lack of quinine-evoked activity in rat trigeminal subnucleus caudalis.
Periodical: Brain Research Index Medicus:
Authors: Simons CT, Boucher Y, Carstens MI, Carstens E ART
Yr: 2003 Vol: 973 Nbr: 2 Abs: Pg: 265 - 274

Challenges for the sensory science from the food and wine industries.
Periodical: Nature Reviews Neuroscience Index Medicus:
Authors: Simons CT, Noble AC ART
Yr: 2003 Vol: 4 Nbr: 7 Abs: Pg: 599 - 606

Oral irritation by mustard oil: self-desensitization and cross-desensitization with capasaicin.
Periodical: Chemical Senses Index Medicus:
Authors: Simons CT, Carstens MI, Marstens E ART
Yr: 2003 Vol: 28 Nbr: 6 Abs: Pg: 459 - 465

Mecamylamine reduces cross-desensitization of trigeminal caudalis neuronal responses to oral chemical irritation.
Periodical: Brain Research Index Medicus:
Authors: Simons CT, Sudo S, Sudo M, Carstens E ART
Yr: 2003 Vol: 1 Nbr: 1-2 Abs: Pg: 249 - 253

Mustard oil has differential effects on the response of trigeminal caudalis neurons to heat and acidity.
Periodical: Pain Index Medicus:
Authors: Simons CT, Sudo S, Sudo M. Carstens M. ART
Yr: 2004 Vol: 110 Nbr: 1-2 Abs: Pg: 64 - 71

Antinociception induced by chronic exposure of rats to cigarette smoke.
Periodical: Neuroscience Letters Index Medicus:
Authors: Anderson KI, Pinkerton KE, Uyeminami D, Simons CT, Carstens MI, Carstens E ART
Yr: 2004 Vol: 366 Nbr: 1-3 Abs: Pg: 86 - 91