1. Metabolic preparatory responses to flavor-nutrient learning and its
effects on subsequent meal patterns
Megan Summers, Sam Sheridan & Kevin Myers, Ph.D
Bucknell University, Lewisburg PA 17837
Subjects
• 17 male rats
• Received intragastric catheters
• Maintained at 85-90% free feeding
body weight
Training
• All subjects tested at least 1 week
post-operation
• Rats received either grape or
cherry flavored, saccharin
sweetened Kool-aid CS+ or CS-
• 16 hour habituation to lick boxes
with 0.2% unflavored saccharin
Alternating days, 16 hour exposure
to a CS+ or CS- flavor with
appropriate intragastric infusion
Testing
• 10 minute access to either CS+ or
CS- flavor + IG 3ml acetaminophen
• Blood sample collection at 0, 10,
30, 60 minutes post ingestion to be
assayed for acetaminophen.
Gastric Emptying
Infusing acetaminophen into
the stomach and taking blood
samples after infusion allows for
analysis of the rate of gastric
emptying.
A spike in acetaminophen
levels would suggest faster rates
of gastric emptying. A gradual
increase in acetaminophen in
blood plasma would demonstrate
a slower rate of gastric emptying,
thus alluding to a controlled
response.
Meal Patterns
In comparison to measuring
chow over a brief access, using
an operant chamber that is
equipped for second by second
resolution of chow consumption,
this experiment can then explore
changes in meal frequency and
meal size of the rats.
From an evolutionary
standpoint, consuming larger
meals of calorically dense food is
more efficient than foraging for
food more often. This has been
believed to be a factor in the
overeating of high calorie foods
seen in society today. New data
shows a different effect of flavor-
nutrient pairing on overeating and
weight gain. A recent study
indicates that individuals who
showed the largest intake of the
flavor paired with intragastric
glucose gained the least amount of
weight on an ad libitum cafeteria
diet (Myers).
In the current study, after
conditioning rats to associate
cherry or grape Kool-Aid flavored
saccharin with either IG glucose or
water infusions, rats were studied
for gastric emptying and meal
patterns. This looks at possible
explanations for how learned
control of metabolic preparatory
responses may be one way flavor-
nutrient learning helps to protect
against weight gain.
Baseline
• 30 min session with 0.2%
unflavored saccharin solution
• 2-hr chow access in operant boxes
Testing
• 30 min session with either 0.2%
CS+ or CS- flavored saccharin
solution + IG water
• 30 min session with either 0.2%
CS+ or CS- flavored saccharin
solution + IG 5ml of 16% glucose
Each session followed by 2-hr chow
access in operant boxes
• Chow patterns measured in both
total grams of pellets consumed as
well as pattern of consumption
Support: STEM Scholar Program
funded by the National Science
Foundation, Douglas K. Candland.
GLUCOSE
CS+
flavor in saccharin
WATER
CS–
flavor in saccharin