ASGSB 1998 Annual Meeting Abstracts

[20]
EFFECTIVENESS OF GROUND BASED MODELS FOR SPACEFLIGHT IN SPLENOCYTE SUBPOPULATIONS.    M.J.Pecaut¹, P.Todd¹, M.Fleshner². ¹BioServe Space Tech, Dept of Aero Engr, U of Colo, CB 429, Boulder, CO. ²Dept of Kinesiology, U of Colo., CB 354, Boulder, CO .

Male Sprague-Dawley rats flown for 10 days aboard the Space Shuttle Endeavor (STS-77) and compared to simultaneous vivarium ground controls exhibited decreases in splenic helper T-cell and neutrophil percentages. There was a simultaneous increase in the percentage of splenic cytotoxic/suppressor T-Cells.

Several aspects of spaceflight may be involved with these population shifts. Launch & landing loads are the primary acute stressors experienced by animals flown on the space shuttle. Cephalic fluid distribution shifts, unloading of the limbs, and exposure to a novel environment are the primary chronic stressors. Two experimental conditions can be used to model either the acute or chronic stressors: centrifugation and anti-orthostatic tail suspension. To date, no consistent immunological changes in the above splenic populations have been observed in either model. This suggests two possible explanations for the spaceflight results: 1) There is something inherently stressful about the space shuttle environment that can not be modeled on the ground; or, 2) The results are due to a combination of acute and chronic stressors.

To further investigate a possible synergistic response, the ground models were combined. 8 male Sprague-Dawley rats were placed into a centrifuge and exposed to forces similar to those experienced during a shuttle launch. After "launch," the animals were suspended to simulate the microgravity portion of a shuttle experiment. After 10 days of suspension, the animals were returned to the centrifuge and "landed." Other groups (n=8/grp) included unlaunched/non-suspended controls and 10 day suspension animals. Upon "landing," the rats were sacrificed and dissected. Splenocytes were labeled with antibodies against CD4, CD8, CD11b, and TCR and analyzed by flow cytometry.

There were no consistent changes in these treatment groups in the cell populations observed. This finding supports the hypothesis that there are stressors unique to the spaceflight environment that can not be fully modeled on the ground.

Back to Meeting Program