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#P196
POSTER SESSION V:
TRIGEMINAL SYSTEM; BEHAVIOR
AND PSYCHOPHYSICS; ODORANT
RECEPTORS & OLFACTION PERIPHERY
Experience-based Enhancement of Preference for Dried-Bonito
Dashi
(a Traditional Japanese fish stock) in Various Rodent
Strains
Takashi Kondoh
1
, Tetsuro Matsunaga
1
, Yoichi Ueta
2
, Etsuro Hori
3
,
Hisao Nishijo
3
1
AJINOMOTO Integrative Research for Advanced Dieting,
Graduate School of Agriculture, Kyoto University Kyoto, Japan,
2
Department of Physiology, School of Medicine, University of
Occupational and Environmental Health Kitakyushu, Japan,
3
System Emotional Science, Graduate School of Medicine and
Pharmaceutical Sciences, University of Toyama Toyama, Japan
The dried-bonito
dashi
is a traditional Japanese fish stock that
improves palatability of various dishes, probably via enhancement
of umami taste. We have found that preference behavior for
dashi
in ascending concentration series varies among rodent strains,
suggesting contribution of some genetic factors for the preference.
Here we compared preference for dried-bonito
dashi
in descending
concentration series with that in ascending ones using 48-h two-
bottle choice tests. The animals used were the adult male Sprague-
Dawley rats, ICR mice, and C57BL/6 mice. The commercial
dashi
employed were the “
Hondzukuri Ichiban-dashi Katsuo
”
(Ajinomoto, Japan) which was 5- to 10-fold dense-taste stock of
hot-water extracted dried bonito. As the dry matter components was
4% (w/w) on a weight basis, the commercial
dashi
was considered
as 4% solution. In the ascending concentration series, preference
for
dashi
was observed between 0.4% and 4% solutions and the
most preferred concentrations were between 1.2% and 2%
solutions. However, the maximal preference varied among rodent
strains with the order of Sprague-Dawley rats (preference ratio,
99%) > ICR mice (80%) > C57BL/6 mice (65%). In the descending
concentration series, the concentration-preference functions of
dashi
shifted to the left for 100 to 1,000-fold and the slop was
gentler compared to those in ascending ones in all strains. As a
result, the preference was observed in wider concentration ranges
(3-4 log units vs. 1 log unit). In C57BL/6 mice, the maximal
preference enhanced greatly compared to ascending ones (95% vs.
65%). These results suggested importance of prior experience of
dashi
for the development of
dashi
preference. Experience-based
enhancement of preference may involve postingestive
consequences associated with
dashi
ingestion.
#P197
POSTER SESSION V:
TRIGEMINAL SYSTEM; BEHAVIOR
AND PSYCHOPHYSICS; ODORANT
RECEPTORS & OLFACTION PERIPHERY
Inhibition of Human Umami Taste Perception By the Lipid
Lowering Drug Clofibrate
Matthew C Kochem
1
, Ashley A Sharples
1
, Suzanne M Alarcon
1
,
Paul AS Breslin
1,2
1
Rutgers University/Department of Nutritional Sciences
New Brunswick, NJ, USA,
2
Monell Chemical Senses Center
Philadelphia, PA, USA
The T1R1-T1R3 receptor is believed to be a principal umami
sensing taste receptor in humans. Umami taste is induced by
monopotassium glutamate (MPG) and is enhanced by inosine
monophosphate (IMP) and guanosine monophosphate (GMP).
It is weakly inhibited by sodium lactisole, which binds to T1R3 in
vitro. We have shown that clofibric acid, a lipid lowering drug
structurally related to lactisole, also inhibits the sweetener receptor
T1R2-T1R3 activity
in vitro
and
in vivo.
Here we wished to
determine if this fibrate drug inhibits umami taste perception in
humans. 12 participants rated the umami intensity of MPG across a
broad range of concentrations. MPG was prepared neat, with 1.37
mM of the T1R1-T1R3 inhibitors Na lactisole and Na clofibrate,
with 3mM of the T1R1-T1R3 enhancers GMP and IMP, and with
combinations of these inhibitors and enhancers. Clofibric acid
inhibited umami intensity for all subjects and was generally a more
potent umami inhibitor than was lactisole. Whereas lactisole
inhibited umami intensity only at low MPG concentrations,
clofibrate inhibited umami intensity across the full range of MPG
concentrations. When prepared with IMP or GMP, umami intensity
was enhanced at low MPG concentrations but was unaffected at
high MPG concentrations. IMP and GMP blunted the inhibitory
effects of clofibric acid and lactisole at low MPG concentrations.
Strikingly, clofibric acid enhanced umami taste at high MPG
concentrations with IMP. In conclusion, the lipid lowering drug
clofibrate inhibits perception of umami in humans and the addition
of IMP or GMP tends to prevent this inhibition at low
concentrations of MPG. Further, clofibrate reciprocally modulates
the effects of the known T1R1-T1R3 enhancers, IMP and GMP, at
high concentrations of MPG. Acknowledgements: Supported by
NIH DC02995 to PASB
#P198
POSTER SESSION V:
TRIGEMINAL SYSTEM; BEHAVIOR
AND PSYCHOPHYSICS; ODORANT
RECEPTORS & OLFACTION PERIPHERY
Diurnal variation of plasma leptin levels and taste recognition
thresholds in over-weight and obese subjects
Keisuke Sanematsu
1
, Masayuki Kitagawa
1
, Yuki Nakamura
1
,
Masatoshi Nomura
2
, Noriatsu Shigemura
1
, Yuzo Ninomiya
1
1
Section of Oral Neuroscience, Graduate School of Dental
Sciences, Kyushu University Fukuoka, Japan,
2
Department of Medicine and Bioregulatory Science, Graduate
School of Medical Sciences, Kyushu University Fukuoka, Japan
Leptin is shown to selectively suppress sweet taste responses in
lean, but not obese diabetic, mice. In humans, sweet taste
recognition thresholds showed diurnal variation that parallel with
variation of plasma leptin levels. Here, we investigated potential
linkage between leptin and sweet taste in over-weight and obese
(OW/Ob) humans. A total of 34 Japanese OW/Ob subjects
(BMI > 25 kg/m
2
) were used to determine recognition thresholds
Abstracts | 93
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