Effects of spaceflight on murine skeletal muscle gene expression. Mus musculus

Spaceflight results in a number of adaptations to skeletal muscle, including atrophy and shifts towards faster muscle fiber types. To identify changes in gene expression that may underlie these adaptations, microarray expression analysis was performed on gastrocnemius from mice flown on the STS-108 shuttle flight (11 days, 19 hours) versus mice maintained on earth for the same period. Additionally, to identify changes that were due to unloading and reloading, microarray analyses were conducted on calf muscle from ground-based mice subjected to hindlimb suspension (12 days) and mice subjected to hindlimb suspension plus a brief period of reloading (3.5 hours) to simulate the time between landing and sacrifice of the spaceflight mice. Overall design: There are five experimental groups in this study: 1) mouse gastrocnemius, spaceflight for 11 days 19hr, n=4; 2) mouse gastrocnemius, animal enclosure module for 11 days, 19h, n=4; 3) mouse calf muscle, hindlimb suspension for 12 days, n=5; 4) mouse calf muscle, hindlimb suspension for 12 days plus reloading for 3.5 hr, n=5; 5) mouse calf muscle, no experimental treatment, n=5.