The Effects of Simulated Microgravity on Sensory Specific
Satiety in Rats Using the Hindlimb Unloading Model
Bio 250 and 450 classes
Presenters: Elizabeth Gowan, Casey Skinner, and Tyler Stinnett Funded by NASA’s South Carolina Space Grant Consortium Research Experience for Undergraduates Grant
Observation: Astronauts get sick in space
• Cephalic Fluid Shift
• Space Adaptation Syndrome
• Dizziness
• Nausea
• Loss of appetite
• Loss of smell and taste
Decreased food intake = insufficient energy intake
Why does this matter?
• Renewed interest in space exploration
• Difficulties reduce productivity
• Cost effectiveness in NASA spending
How can we increase astronauts’ food consumption?
Study humans in simulated microgravity
Difficult and cost-prohibitive
Animal model of simulated microgravity?
•Yes! >800 papers published using this animal model
•None have attempted to manipulate feeding behaviors
Is there an animal model of increased eating?
Sensory Specific Satiety (Ahn and Phillips, 1999)
A hungry rat fed until satiated on rat chow WILL NOT eat more rat chow
A hungry rat fed until satiated on rat chow WILL eat Froot Loops ®
Purpose:
• To combine an existing model of simulated microgravity with an existing model of increased eating
Hypothesis:
• Rats exhibit sensory specific satiety under conditions of simulated microgravity.
Methods• 7 Male Sprague-Dawley Rats
• Fed Rat Chow ad-libitum except on experimental days
• Used NASA Hindlimb Unloading Model
•Institutional Animal Care and Use Committee Approved
What is the Hindlimb Unloading Model?
• Simulates microgravity (Morey-Holton & Globus, 2002.)
– Cephalic Fluid Shift– Symptoms of Space Adaptation Syndrome
2 week
recovery period
Horizontal
Week 1
body weight & food intake measured twice daily
Experimental Time Line
1 week recovery period
1 week recovery period
HU
Week 3
HU
Week 6
Horizontal
Week 8
Weekly Procedures
Meal 1 - 90 minutesRat Chow
Meal 2 - 30 MinutesRat Chow or Froot Loops(same caloric densities)
- Counterbalanced
• Experiment• Returned to standard cages
Day 7
• Transferred to experimental cage• 14-18 hr food deprivation begins
Day 0-1
• Experiment
Day 2
• Hanging out in the
experimental cage!
Days 3-5
• 14-18 hr food deprivation begins
Day 6
Food deprivation
How SSS was measured...• Food Intake (grams):
• Meal 1 at 60 and 90 minutes• Meal 2 at 30 minutes
Statistical Analysis• Two Way Repeated Measures ANOVA
•Student-Newman-Keuls Test *p<0.05
• Latency to Eat (minutes):• Meal 2
Treatment
Horiz D2 HU D2 Horiz D7 HU D7
Cu
mu
lati
ve F
oo
d In
take
(g
ram
s)
0
1
2
3
4
5
6
7
8
~50%
*~50%
*
Meal 1 Food Intake at 60 and 90 Minutes
Treatment
Horiz D2 HU D2 Horiz D7 HU D7
La
ten
cy
to
fe
ed
(m
in)
0
10
20
30
40 Rat chow/Rat chowRat chow/Froot loops
Latency to Eat Meal 2
**
*
*
Treatment
Horiz D2 HU D2 Horiz D7 HU D7
Cu
mu
lati
ve F
oo
d In
take
(g
ram
s)
0
1
2
3
4 Rat chow/Rat chowRat chow/ Froot Loops
Meal 2 Food Intake at 30 minutes
*
*
*
**
~40%
~40%
*
Conclusions:
• Rats in Hindlimb Unloading model exhibit Sensory Specific Satiety.
• Rats in Hindlimb Unloading model eat significantly less than their horizontal counterparts.
Relevance:
• How does this relate to astronauts?
• Future Directions:– Promote increased energy intake
• Manipulate sensory properties• Increase caloric density
Acknowledgements:
• Funded by a grant awarded to Drs. Davis and Hettes from NASA’s South Carolina Space Grant Consortium.
The Effects of Simulated Microgravity on Sensory Specific
Satiety in Rats Using the Hindlimb Unloading Model
Bio 250 and 450 classes
Presenters: Elizabeth Gowan, Casey Skinner, and Tyler Stinnett Funded by NASA’s South Carolina Space Grant Consortium Research Experience for Undergraduates Grant
Latency to Feed Meal 1
Overnight Food Intake
