Abstracts - Association for Chemoreception Sciences

P O S T E R S
short-term licking responses to the following solutions: 167, 250
and 333 mM glucose (G), 167, 250 and 333 mM fructose (F), 38
mM saccharin (S), and binary mixtures of G+S and F+S. There
was a high correlation between the two measures of taste
responsiveness. Both indicated that the mice show higher taste
responsiveness to (i) G+S and F+S than any single sweetener, (ii)
S than any concentration of F or G, and (iii) F than isomolar
concentrations of G. In Experiment 2, asked whether daily intake
of these solutions increased with taste responsiveness. No such
relationship was observed, however. For instance, the G solutions
elicited the weakest taste responses, but the greatest intake. In
contrast, the F+S, F and S solutions elicited the strongest taste
responses, but the weakest intake. These findings indicate that
taste does not determine daily intake of dilute sugar solutions.
We propose, instead, that daily intake is controlled primarily by
the extent to which a sugar solution stimulates intestinal nutrient
detectors. This proposition is based on studies showing that
G provides substantially more positive post-oral reinforcement of
feeding than F. Acknowledgements: Supported in part by a grant
from the HHMI to Barnard College
#P270 POSTER SESSION VI:
PERIPHERAL AND CENTRAL TASTE;
PERIPHERAL OLFACTION
Glucose utilization supports preferences for sugars in mice
Xueying Ren 1,2 , Jozelia G Ferreira 1,2 , Sara J Shammah-Lagnado 3 ,
Catherine W Yeckel 1,4 , Ivan E de Araujo 1,2
1
The John B. Pierce Laboratory New Haven, CT, USA,
2
Psychiatry, Yale School of Medicine New Haven, CT, USA,
3
Physiology, Institute of Biological Sciences Sao Paulo, Brazil,
4
Epidemiology and Public Health, Yale School of Medicine New
Haven, CT, USA
We are investigating the role of glucose utilization as a rewarding
postingestive factor influencing carbohydrate intake
independently of sweetness perception. C57BL6 mice fitted with
gastric catheters were given access to a water-containing recipient
such that an infusion pump connected to the gastric catheter was
activated whenever licks to water were detected. We first show
that in this paradigm mice will consume significantly higher levels
of water when gastrically infused with glucose compared to when
infused with L-serine, an amino acid known to be a weak
promoter of glucose utilization. This finding did not depend on
nutrient-specific gastrointestinal absorption since jugular rather
than intragastric infusions produced essentially the same effect.
We then verified whether these sweet-independent responses to
glucose infusion were altered by disrupting glucose utilization
with intravenous infusions of 2-deoxyglucose (2-DG, a glucose
analogue that does not undergo complete glycolysis). Finally,
microdialysis measurements were performed to test whether
intravenous 2-DG infusions can alter dopaminergic response
patterns in reward circuits that under normal conditions are
observed upon nutrient intake. These preliminary findings suggest
that preferences for carbohydrates over other nutrients might
develop independently of taste quality, and that metabolic signals
generated during the catabolism of glucose molecules might
reinforce preferences for sugars over other nutrients.
Acknowledgements: The J. B. Pierce Laboratory
#P271 POSTER SESSION VI:
PERIPHERAL AND CENTRAL TASTE;
PERIPHERAL OLFACTION
Oxytocin Enhances Brief-Access Taste Preference for Sweet
and Umami Stimuli
Michael S. Sinclair 1 , Steven J. St. John 2 , Nirupa Chaudhari 1,3
1
Program in Neurosciences, University of Miami Miller School of
Medicine Miami, FL, USA, 2 Department of Psychology, Rollins
College Winter Park, FL, USA, 3 Department of Physiology and
Biophysics, University of Miami Miller School of Medicine Miami,
FL, USA
The neurohormone oxytocin (OXT), known for facilitating
lactation, parturition, and social behaviors, also inhibits ingestion.
Mice lacking OXT previously were shown to overconsume sweet
and carbohydrate solutions compared to wild-types. The apparent
preference for sweet stimuli was attributed to a diminished postingestive
satiety for carbohydrates (Sclafani et al, 2007). We
recently showed that OXT receptor is expressed and functional in
some cells in mouse taste buds. We therefore asked if circulating
OXT alters the taste preferences of wild-type mice. We injected
12 water-deprived C57BL/6 mice (6 males, 6 females)
intraperitoneally with 10 mg/kg body weight OXT or an equal
volume saline. Thirty min later, we tested them in a Davis briefaccess
lickometer, using concentrations of tastants that give midrange
behavioral responses: 0.3M NaCl (salty), 0.02M citric acid
(sour), 0.3mM quinine HCl (bitter), 10mM Na-saccharin (sweet),
0.1M MSG with 500µM inosine monophosphate (IMP) (umami),
and water. Animals were tested once daily for 6 days, and given
OXT or saline on alternating days. For each tastant, we calculated
lick ratios as lick rate for tastant / lick rate for water. OXT
significantly increased the lick ratio for saccharin (1.62±0.15 vs.
1.08±0.04) and for MSG+IMP (1.44±0.17 vs. 1.05±0.03) but not
for other tastants. OXT decreased lick rates to all solutions and to
water as expected from its effect on ingestion. However, the lick
rates to saccharin and to MSG+IMP were decreased less than for
water, resulting in higher lick ratios. There were no differences
between males and females. Thus, systemic OXT decreases fluid
intake overall while enhancing preference for palatable (sweet and
umami) tastes. To what extent this is due to action on peripheral
vs. central sites remains to be investigated. Acknowledgements:
Supported by NIH/NIDCD grants R01DC6021, R21DC10078
and American Heart Association Predoctoral Fellowship
0815215E.
#P272 POSTER SESSION VI:
PERIPHERAL AND CENTRAL TASTE;
PERIPHERAL OLFACTION
Generalization of conditioned taste aversion (CTA) to
guanosine 5’-monophosphate (GMP) in C57BL/6 mice
Yuko Murata 1 , Alexander A. Bachmanov 2
1
National Research Institute of Fisheries Science Yokohama, Japan,
2
Monell Chemical Senses Center Philadelphia, PA, USA
Guanosine, inosine and adenosine 5’-monophosphates (GMP,
IMP and AMP) have synergistic effects on umami taste of MSG in
humans (Yamaguchi, 1967), and on taste responses of the rat
chorda tympani nerve to various amino acids (Yoshii, 1987).
These purine 5’-ribonucleotides however differ in whether they
evoke an umami taste without MSG: IMP and GMP alone have a
distinct umami taste, but AMP is almost tasteless to humans
(Yamaguchi, 1967). Only a few studies have examined taste
116 | AChemS Abstracts 2010 Abstracts are printed as submitted by the author(s)