Abstract
G protein-coupled receptors that signal bitter taste (T2Rs) are expressed in the mucosal lining of the oral cavity and gastrointestinal (GI) tract. In mice, intragastric infusion of T2R ligands activates Fos expression within the caudal viscerosensory portion of the nucleus of the solitary tract (NTS) through a vagal pathway (Hao S, Sternini C, Raybould HE. Am J Physiol Regul Integr Comp Physiol 294: R33-R38, 2008). The present study was performed in rats to further characterize the distribution and chemical phenotypes of brain stem and forebrain neurons activated to express Fos after intragastric gavage of T2R ligands, and to determine a potential behavioral correlate of this central neural activation. Compared with relatively low brain stem and forebrain Fos expression in control rats gavaged intragastrically with water, rats gavaged intragastrically with T2R ligands displayed significantly increased activation of neurons within the caudal medial (visceral) NTS and caudal ventrolateral medulla, including noradrenergic neurons, and within the lateral parabrachial nucleus, central nucleus of the amygdala, and paraventricular nucleus of the hypothalamus. A behavioral correlate of this Fos activation was evidenced when rats avoided consuming flavors that previously were paired with intragastric gavage of T2R ligands. While unconditioned aversive responses to bitter tastants in the oral cavity are often sufficient to inhibit further consumption, a second line of defense may be provided postingestively by ligand-induced signaling at GI T2Rs that signal the brain via vagal sensory inputs to the caudal medulla.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Regulatory Integrative and Comparative Physiology |
| Volume | 296 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 2009 |
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Keywords
- Brain stem
- Denatonium
- Forebrain
- Nucleus of the solitary tract
ASJC Scopus subject areas
- Physiology
- Physiology (medical)
Cite this
Central Fos expression and conditioned flavor avoidance in rats following intragastric administration of bitter taste receptor ligands. / Hao, Shuzhen; Dulake, Michelle; Espero, Elvis; Sternini, Catia; Raybould, Helen E; Rinaman, Linda.
In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 296, No. 3, 03.2009.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Central Fos expression and conditioned flavor avoidance in rats following intragastric administration of bitter taste receptor ligands
AU - Hao, Shuzhen
AU - Dulake, Michelle
AU - Espero, Elvis
AU - Sternini, Catia
AU - Raybould, Helen E
AU - Rinaman, Linda
PY - 2009/3
Y1 - 2009/3
N2 - G protein-coupled receptors that signal bitter taste (T2Rs) are expressed in the mucosal lining of the oral cavity and gastrointestinal (GI) tract. In mice, intragastric infusion of T2R ligands activates Fos expression within the caudal viscerosensory portion of the nucleus of the solitary tract (NTS) through a vagal pathway (Hao S, Sternini C, Raybould HE. Am J Physiol Regul Integr Comp Physiol 294: R33-R38, 2008). The present study was performed in rats to further characterize the distribution and chemical phenotypes of brain stem and forebrain neurons activated to express Fos after intragastric gavage of T2R ligands, and to determine a potential behavioral correlate of this central neural activation. Compared with relatively low brain stem and forebrain Fos expression in control rats gavaged intragastrically with water, rats gavaged intragastrically with T2R ligands displayed significantly increased activation of neurons within the caudal medial (visceral) NTS and caudal ventrolateral medulla, including noradrenergic neurons, and within the lateral parabrachial nucleus, central nucleus of the amygdala, and paraventricular nucleus of the hypothalamus. A behavioral correlate of this Fos activation was evidenced when rats avoided consuming flavors that previously were paired with intragastric gavage of T2R ligands. While unconditioned aversive responses to bitter tastants in the oral cavity are often sufficient to inhibit further consumption, a second line of defense may be provided postingestively by ligand-induced signaling at GI T2Rs that signal the brain via vagal sensory inputs to the caudal medulla.
AB - G protein-coupled receptors that signal bitter taste (T2Rs) are expressed in the mucosal lining of the oral cavity and gastrointestinal (GI) tract. In mice, intragastric infusion of T2R ligands activates Fos expression within the caudal viscerosensory portion of the nucleus of the solitary tract (NTS) through a vagal pathway (Hao S, Sternini C, Raybould HE. Am J Physiol Regul Integr Comp Physiol 294: R33-R38, 2008). The present study was performed in rats to further characterize the distribution and chemical phenotypes of brain stem and forebrain neurons activated to express Fos after intragastric gavage of T2R ligands, and to determine a potential behavioral correlate of this central neural activation. Compared with relatively low brain stem and forebrain Fos expression in control rats gavaged intragastrically with water, rats gavaged intragastrically with T2R ligands displayed significantly increased activation of neurons within the caudal medial (visceral) NTS and caudal ventrolateral medulla, including noradrenergic neurons, and within the lateral parabrachial nucleus, central nucleus of the amygdala, and paraventricular nucleus of the hypothalamus. A behavioral correlate of this Fos activation was evidenced when rats avoided consuming flavors that previously were paired with intragastric gavage of T2R ligands. While unconditioned aversive responses to bitter tastants in the oral cavity are often sufficient to inhibit further consumption, a second line of defense may be provided postingestively by ligand-induced signaling at GI T2Rs that signal the brain via vagal sensory inputs to the caudal medulla.
KW - Brain stem
KW - Denatonium
KW - Forebrain
KW - Nucleus of the solitary tract
UR - http://www.scopus.com/inward/record.url?scp=64149086122&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=64149086122&partnerID=8YFLogxK
U2 - 10.1152/ajpregu.90423.2008
DO - 10.1152/ajpregu.90423.2008
M3 - Article
C2 - 19073908
AN - SCOPUS:64149086122
VL - 296
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
SN - 1931-857X
IS - 3
ER -