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Effects of nicotine on taste processing

Institution: University of California, Davis
Investigator(s): Christopher Simons, Ph.D.
Award Cycle: 2001 (Cycle 10) Grant #: 10DT-0197 Award: $24,834
Subject Area: Nicotine Dependence
Award Type: Dissertation Awards
Abstracts

Initial Award Abstract
The goal of this new proposal is to detail nicotine’s effect on taste processing. We believe that nicotine changes the way foods taste making them less palatable so that people lose weight. We propose to test this belief by studying (1) electrical activity in rat nerve fibers and (2) human perceptual responses.

Nicotine: Taste Processing. Nicotine has 2 properties that may cause it to suppress taste sensations. Because it is bitter, nicotine may reduce the electrical activity in taste nerves induced by other tastes. Others have shown quinine’s ability to suppress sweetness-induced nerve activity. Alternatively, nicotine elicits a painful sensation when it contacts the mouth. We have found that another pain-inducing chemical, capsaicin (the chemical that gives chili pepper its pungency) reduces the electrical activity in taste nerves when it is applied to the tongue prior to application of taste solutions. Using these same methods, we will investigate whether tastant-induced nerve activity changes following application of nicotine or quinine (a bitter substance) to the tongue. By comparing the effects of nicotine to quinine, we can begin to determine whether nicotine’s effect is due to its taste- or pain-inducing properties.

We will also study the effects of nicotine on human taste perception. We believe that nicotine will lower the intensity of tastes. This will be tested by using suprathreshold concentrations of model taste solutions as well as real foods. This presents a completely novel aspect of our proposal in that no previous data has been generated using actual food products. Additionally, previous studies have shown that nicotine or smoking increases the threshold at which tastes are detected so that perception occurs only at higher than normal tastant concentrations. Unfortunately, these previous studies used psychological tests that unknowingly introduced bias into the results rendering them unusable. Currently, we are assessing the role capsaicin plays in suppressing human assessments of taste intensity. We will use this same approach to determine if nicotine also reduces perceptions of taste. To assess the effect of nicotine on taste thresholds, we will employ a bias-free paradigm that has proven very useful in taste threshold experiments.

Nicotine: Irritation. Preliminary studies have revealed the presence of nerve cells within the taste area of the brain that respond, not to tastants, but exclusively to painful stimuli, including nicotine, directed at the tongue. This novel finding suggests that areas of the brain previously thought to be uninvolved in pain, may actually process this type of information. Nerve cells residing in the region of the brain that normally receives pain signals from the oral cavity show a decrease in electrical activity with repeated or continuous application of nicotine to the tongue. We believe that pain cells within the taste area of the brain will respond in a manner identical to those in the pain processing region. We will test this belief by using techniques that will allow us to measure and record electrical activity of these neurons following repeated application of nicotine to the tongue.
Publications

Taste suppression following lingual capsaicin pre-treatment in humans.
Periodical: Chemical Senses Index Medicus:
Authors: Simons CT, O'Mahony M, Carstens E ART
Yr: 2002 Vol: 27 Nbr: Abs: Pg: 353-365

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 C.T., Faurion A, Azerad J, Carstens E ART
Yr: 2003 Vol: Nbr: Abs: Pg:

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: 2001 Vol: Nbr: Abs: Pg:

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: Nbr: Abs: Pg:

Irritant-gustatory interactions: suppression of tastant-evoked responses of neurons in the nucleus of the soitary tract (NTS) by oral capsaicin.
Periodical: Society for Neuroscience Abstracts Index Medicus:
Authors: Simons CT, Boucher Y, Carstens E ABS
Yr: 2001 Vol: Nbr: Abs: Pg:

Nicotine suppression of tastant-evoked neural activity in the rat.
Periodical: Association for Chemoreception Sciences Index Medicus:
Authors: Simons CT, Boucher Y, Carstens E ABS
Yr: 2002 Vol: Nbr: Abs: Pg:

Gustatory-irritant interactions: suppression of taste by oral capsaicin.
Periodical: Association for Chemoreception Sciences Index Medicus:
Authors: Sinons CT, Boucher Y, Carstens E ABS
Yr: 2002 Vol: Nbr: Abs: Pg:

Activation of brainstem neurons by irritant chemical stimulation of the throat assessed by c-fos immunohistochemistry.
Periodical: Society for Neuroscience Abstracts Index Medicus:
Authors: Cuellar JM, Boucher Y, Simons CT, Jung SW, Carstens MI, Carstens E ABS
Yr: 2002 Vol: Nbr: Abs: Pg: