Abstracts - Association for Chemoreception Sciences

from postoral sites are integrated with oral taste-guided behaviors
is unknown. This study examined effects of intraduodenal (ID)
infusions of a sweet ligand on conditioned and unconditioned
affective responses to matching oral chemosensory stimuli.
First, rats were given two separate 15 min sessions to ingest
0.3M sucrose directly followed by either ip LiCl (3 mEq/
kg) to condition a sucrose taste aversion (CTA, n=9) or saline
(unconditioned, n=8). Then, licking responses to 5 sucrose
concentrations (0.01, 0.03, 0.1, 0.3, 1M), 0.12M NaCl, and water
(10s trials in randomized blocks) were examined in two 30 min
brief-access tests. Four min before each test, rats were infused
ID with 0.3M sucrose or 0.15M NaCl (3ml). For unconditioned
rats, ID sucrose enhanced preferential licking to 0.03-1 M oral
sucrose, with no effect on licking for NaCl. This preference
shift emerged rapidly by trial block 2. CTA rats reduced licking
to 0.03-1M sucrose, not NaCl, but because CTA rats initiated
so few trials, and significantly fewer after ID sucrose versus ID
NaCl, detection of emergent differences due to ID preload type
was likely limited. Thus, a taste reactivity test was conducted
in a separate group of CTA rats. ID 0.3M sucrose preload
(n=6) significantly increased gaping to intraoral 0.3M sucrose
infusions (0.5ml/30s every 3min for 15min) relative to ID 0.15M
NaCl preload (n=7). Together, the results suggest postoral
stimuli impact oral taste processing in chemospecific ways.
Acknowledgements: NIH-T32DC000044
#P177 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
An interaction of chronic and acute metabolic states on
olfactory perception associated with ghrelin signaling
Xue Sun, Marga G Veldhuizen, Dana M Small
The John B. Pierce Laboratory and Yale University New Haven,
CT, USA
Olfaction is key for the evaluation of food cues in the
environment. It is therefore not surprising that evidence is
emerging for metabolic influences in olfaction. For example,
receptors for feeding-related molecules such as ghrelin are
expressed within the olfactory system and olfactory sensitivity
is increased in fasted vs. fed state in rodents. However, human
studies have generated conflicting results. This study tested
whether the influence of acute homeostatic state (fasted vs.
fed) on olfactory perception could be moderated by body mass
index, which is associated with chronic metabolic alterations.
Twenty-one subjects (14 healthy weight/HW, BMI M=22.3
SD=1.9; 7 overweight/OW, BMI M=28.2 SD=2.8) rated the
intensity of odors (chocolate, strawberry, honeysuckle and
lilac) and tastes (chocolate and strawberry flavored milk) using
the general labeled magnitude scale in fed and fasted states
(separate counterbalanced days), concomitant to an fMRI
study. Blood samples were also collected on a subset of subjects
(n=15) to assess the influence of internal state on feeding-related
molecules. A repeated measures ANOVA of intensity
ratings revealed a 3-way interaction between state
(fed vs. fasted), stimulus (odors vs. taste) and group (HW vs.
OW) (f(1,19)=7.52, p=.013), where odor intensity ratings
decreased significantly in fed vs. fasted for OW but not HW
subjects. Critically, the difference in odor intensity ratings
between fasted and fed correlated negatively with difference in
ghrelin change from baseline between fasted and fed conditions
(r(13)=-.615, p=.016); the smaller the change in intensity
perception, the larger the change in ghrelin levels. These findings
demonstrate that chronic and acute metabolic states interact to
influence olfactory perception possibly through ghrelin signaling.
Acknowledgements: Supported by R01 DK085579.
#P178 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
Oral Sweet Taste Stimulation Induces Cephalic Phase
Carbohydrate Oxidation in Humans
Sze Yen Tan, Richard D. Mattes
Purdue University/Department of Nutrition Science West
Lafayette, IN, USA
Objective: Sensory stimuli induce many anticipatory reflexes.
Specifically, oral sweet taste stimulation increases glucose
absorption in rats and induces cephalic phase insulin release
in animals and humans. This study aimed to investigate
whether oral sweet taste stimulation also induces an acute
increase of carbohydrate oxidation in humans. Methods: This
was a randomized, crossover design study with two test visits
delivering: 1) control (DI water) and 2) 10% sucrose (w/w)
solutions orally. An indirect hood calorimeter was used to
measure energy expenditure (EE) and respiratory quotient (RQ)
through gaseous exchanges. Each measurement was performed
at one to two hours after habitual breakfast or lunch, where
participants were instructed to consume an identical meal at
identical times before their visits. Calorimeter measurement
was preceded by a 30-minute habituation period, followed by
oral stimulation and subsequent measurement for 30 minutes.
Changes in EE and RQ were tested using a general linear
model for repeated measures ANOVA in SPSS. Results: Nine
participants have completed the study (8 females and 1 male,
mean age=25.2 ± 4.6 years, mean weight=59.2 ± 4.3kg, mean
BMI=21.6 ± 2.5kgm -2 ). Energy expenditure following test
solution stimulation did not change and was not significantly
different between solutions (time and interaction effects, P>0.05).
However, RQ was significantly increased after sweet taste
stimulation (time effects, p