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 minutes Rat Chow Meal Minutes Rat Chow or Froot Loops (same caloric densities) - Counterbalanced Experiment Returned to standard cages Day 7 Transferred to experimental cage hr food deprivation begins Day 0-1 Experiment Day 2 Hanging out in the experimental cage! Days 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

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

Latency to Eat Meal 2 * * * *

Meal 2 Food Intake at 30 minutes * * * * * ~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