Abstracts - Association for Chemoreception Sciences

glutamate and monopotassium glutamate. Subjects tasted the
mixture by repeated swishing and spitting for 5 minutes. Subjects
then ingested another dose of glutamate. Baseline blood samples
were collected every 5 minutes before ingestion of glutamate.
After ingestion, samples were collected at 3 minute intervals
for a total of 15 minutes and analyzed for glucose, insulin and
c-peptide. To assess glutamate sensitivity, subjects tasted and
rated intensity matched NaCl, sucrose, and glutamate solutions.
Relative glutamate sensitivity was defined as the ratio of
perceived glutamate intensity to that of NaCl and sucrose. All
seven subjects showed pre-absorptive blood glucose changes in
response to the taste of glutamate. Six subjects showed increases
in blood glucose (presumably due to glucagon release) and one
subject showed a decrease. Half of the subjects showed preabsorptive
changes in insulin. The highest PIRs occurred in the
two subjects who showed the highest sensitivity to glutamate.
The lowest PIR occurred in the subject with the lowest sensitivity
to glutamate. Acknowledgements: NIH DC02995
the control of dietary fat intake and that these effects appear
to be significantly influenced by gender. Acknowledgements:
Supported by NIH grant R01DK059611 (TAG)
#P173 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
Human Anticipatory Blood Pressure Responses to Oral
NaCl and KCl are Different
Melissa A Murphy 1 , Paul A.S. Breslin 1,2
1
Department of Nutritional Sciences, Rutgers University New
Brunswick, NJ, USA, 2 Monell Chemical Senses Center Philadelphia,
PA, USA
#P172 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
Mice lacking Trpm5 show reduced dietary fat intake
Dulce M. Minaya, Jacqueline Lee, Dane R. Hansen,
Timothy A. Gilbertson
Utah State University/Biology Department Logan, UT, USA
We recently showed a critical role of Trpm5 in the transduction
pathway for long chain polyunsaturated fatty acids (Liu et al., J
Neurosci 31: 8634, 2011). In the present study, we have begun to
investigate dietary fat preference and the propensity to develop
dietary-induced obesity in mice lacking Trpm5. In male mice
placed on a high fat diet, those mice lacking Trpm5 (Trpm5 -/- )
ate significantly less and accordingly weighed less and had less
body fat than wild type (Trpm5 +/+ ) mice; no differences between
Trpm5 -/- and Trpm5 +/+ mice were seen on a control (low fat) diet.
Similar differences were recorded in control male mice and those
lacking IP 3
R 3
, receptors that are upstream of Trpm5 activation in
the fatty acid transduction pathway. Most surprisingly, however,
was the fact that female mice with or without IP 3
R 3
did not
show the same differences indicating a potential gender effect
of this pathway on dietary fat intake. Given these data, we have
performed feeding studies on female Trpm5 -/- and Trpm5 +/+
mice to look for similar gender-specific effects on fat intake.
Like male mice, female mice lacking Trpm5 show a decrease in
dietary fat intake and gain less weight than wild types, though
these effects are much less robust and have a much slower onset
than for the male mice. However, unlike the males, there is no
significant difference in body fat between female Trpm5 -/- and
Trpm5 +/+ after being on the high fat diet for 56 days. We are
currently exploring the specificity of these effects for the different
classes of fat (saturated versus unsaturated). Together, our data
indicate that Trpm5 may play a role, directly or indirectly, in
The mechanism of association between dietary sodium
and blood pressure is not clearly defined, but high dietary
salt intake is considered a risk for hypertension (HTN) and
cardiovascular disease (CVD). Many studies have examined
the impact of different dietary cations on these risk factors
and implicate sodium (or Na/K ratio) as a key determinant.
We previously presented data showing an anticipatory blood
pressure (BP) response to the oral presentation of 1.0 Molar
NaCl and suggested this may be linked to blood volume preabsorptive
reflexes. Based on this premise, we hypothesized
that this anticipatory reflex would be more pronounced for
sodium ions. To determine the specificity of the response to oral
sodium, subjects rinsed orally with either 0.5 M KCl (matched
for taste intensity to NaCl) to test cation composition and 1.0
M Na-Gluconate to test salt taste intensity. Subjects rested
in a seated position for 2.5 hours while we recorded resting
BP and additional readings following the rinse at 10 minute
intervals with a manual sphygmomanometer, one trial per day,
five trials for each solution tested. In subjects whose blood
pressure dropped following a rinse with NaCl, a similar trend
was observed after a rinse with Na-Gluconate. Yet BP remained
level, without a decreasing trend, following a rinse with KCl.
Interestingly, the BP response to Na-Gluconate was weaker than
the NaCl response, suggesting an influence of taste perception
on the anticipatory BP reflex. The difference between the BP
response to NaCl and to KCl suggests that there may be oral
chemosensory specificity to the reflex. These data support the
idea that anticipatory BP reflexes are cation specific and may
involve gustatory mechanisms. Acknowledgements: Funded in
part by NIH DC 02995 to PASB.
POSTER PRESENTATIONS
Abstracts are printed as submitted by the author(s).
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