Project Leader: Tyler Stinnett Funded by NASA’s South Carolina Space Grant Consortium Research Experience for Undergradu

1. Manipulating the Sensory Properties of Food Enhances Food Intake in Rats Under Simulated Microgravity: a Demonstration of Sensory Specific Satiety with the Hindlimb Unloaded Model Project Leader: Tyler Stinnett Funded by NASA’s South Carolina Space Grant Consortium Research Experience for Undergraduates Grant

2. Decreased food intake = Insufficient energy intake = Decrease in mission productivity Observation: Astronauts are not eating enough • Cephalic Fluid Shift • Space Adaptation Syndrome • Dizziness • Nausea • Loss of appetite • Reduction of smell and taste

3. Difficult and cost-prohibitive How can we increase astronauts’ food consumption? Study humans in simulated microgravity Animal model of simulated microgravity? • Yes! >800 papers published using this animal model (Morey-Holton and Globus, 2002) • However, we are unaware of anyprevious attempts to manipulate feeding behaviors

4. A hungry rat fed until satiated on rat chow WILL NOT eat more rat chow A hungry rat fed until satiated on rat chow WILLeat Froot Loops® Is there an animal model of increased eating? Yes! Sensory Specific Satiety (Rolls, et al, Brain Research, 1986; Ahn and Phillips, 1999)

5. Hypothesis: • Rats exhibit sensory specific satiety under conditions of simulated microgravity. Purpose: • To combine an existing model of simulated microgravity with an existing model of increased eating

6. Methods • 7 male Sprague-Dawley rats • Fed rat chow ad libitum except on experimental days • Used NASA Hindlimb Unloaded Model

7. Our Modifications to the Hindlimb Unloading Apparatus • Need for more affordable and space saving cage • Collapsible • Easy angle adjuster • 2 sides with rollers are taller for rats over 500g • Disposable bedding tray

8. 2 week recovery period 1 week recovery period 1 week recovery period HU Horizontal Horizontal HU Week 1 Week 3 Week 6 Week 8 Experimental Time Line body weight & food intake measured twice daily

9. Day 0-1 Day 2 Days 3-5 Day 6 Day 7 • Day 0: Transferred to experimental cage • Day 1: 14-18 hr food deprivation begins • Experiment • Continuation of tail suspension • 14-18 hr food deprivation begins • Experiment • Returned to standard cages Meal 1 - 90 minutes Rat Chow Meal 2 - 30 Minutes Rat Chow or Froot Loops® (same caloric densities) - Counterbalanced Weekly Procedures Food deprivation

10. Statistical Analysis • Two way repeated measures ANOVA • Student-Newman-Keuls post hoc test *p<0.05 How SSS was measured... • Cumulative Food Intake (grams): • Meal 1 at 60 and 90 minutes • Meal 2 at 30 minutes • Latency to Eat in Meal 2 (minutes): • Latency- the time between access to and consuming the first bite of food

11. Three Components of Sensory Specific Satiety #1: Satiated Animal Satiated- does not consume available food.

12. * * ~50% ~50% Meal 1 Food Intake at 60 and 90 Minutes

13. Three Components of Sensory Specific Satiety #1: Satiated Animal #2: Decreased Latency to feed on a more palatable second meal

14. * * * * Latency to Eat Meal 2 Reminder: Latency is the time between food presentation and the first bite.

15. Three Components of Sensory Specific Satiety #1: Satiated animal #2: Decreased latency to feed on a more palatable second meal #3: Increased intake of a more palatable second meal

16. * * * * * ~40% ~40% * Meal 2 Food Intake at 30 minutes

17. Summary: • Rats in the Hindlimb Unloaded model exhibit Sensory Specific Satiety by consuming more Froot Loops® than rat chow. • Rats in the Hindlimb Unloaded model eat significantly less than their horizontal counterparts.

18. Conclusions: • Rats in simulated microgravity show decreased food intake, however, intake can be augmented by manipulating sensory properties of food.

19. Neural Activity (action potentials/ sec) rejects glucose Repeated offerings of 50 ml portions of glucose Future Directions: What Part(s) of the Brain Regulates Overeating During Sensory Specific Satiety? Taken from Rolls et al, 1986 Neural Activity in the Lateral Hypothalamus (LH)

20. Manipulating the Sensory Properties of Food Enhances Food Intake in Rats Under Simulated Microgravity: a Demonstration of Sensory Specific Satiety with the Hindlimb Unloaded Model Project Leader: Tyler Stinnett Funded by NASA’s South Carolina Space Grant Consortium Research Experience for Undergraduates Grant