Effects of gravitational loading levels on protein expression related to metabolic and/or morphologic properties of mouse neck muscles
Tomotaka Ohira, Takashi Ohira, Fuminori Kawano...et al. ; ASI sponsor
Jan - 2014
DOI: 10.1002/phy2.183
ISSN : 2051-817X ;
journal : Physiological Reports

Volume : 2 ; Issue : 1
type: Article Journal

The effects of 3 months of spaceflight (SF), hindlimb suspension, or exposureto 2G on the characteristics of neck muscle in mice were studied. Three8-week-old male C57BL/10J wild-type mice were exposed to microgravity onthe International Space Station in mouse drawer system (MDS) project,although only one mouse returned to the Earth alive. Housing of mice in asmall MDS cage (11.6 9 9.8-cm and 8.4-cm height) and/or in a regular vivar-ium cage was also performed as the ground controls. Furthermore, ground-based hindlimb suspension and 2G exposure by using animal centrifuge(n = 5 each group) were performed. SF-related shift of fiber phenotype fromtype I to II and atrophy of type I fibers were noted. Shift of fiber phenotypewas related to downregulation of mitochondrial proteins and upregulation ofglycolytic proteins, suggesting a shift from oxidative to glycolytic metabolism.The responses of proteins related to calcium handling, myofibrillar structure,and heat stress were also closely related to the shift of muscular propertiestoward fast-twitch type. Surprisingly, responses of proteins to 2G exposureand hindlimb suspension were similar to SF, although the shift of fiber typesand atrophy were not statistically significant. These phenomena may be relatedto the behavior of mice that the relaxed posture without lifting their head upwas maintained after about 2 weeks. It was suggested that inhibition of nor-mal muscular activities associated with gravitational unloading causes signifi-cant changes in the protein expression related to metabolic and/ormorphological properties in mouse neck muscle.

keywords : mouse neck muscle, gravitational unloading,protein expression