Age‐dependent changes in gene expression in rat soleus muscles after hindlimb suspension

Abstract

Soleus muscles from young and old rats were used to test the hypothesis that aging is associated with distinct changes in gene expression in response to disuse atrophy. Atrophy was induced by hind limb suspension (HS) for 14 days in male Fisher 344/BN rats of 6 or 32 months of age. Gene expression was determined by spotted microarray analysis and verified for selected genes by real time RT-PCR. Heat shock protein genes were down regulated with HS in both young and old and those encoding extracellular matrix proteins were also changed to similar extent at both ages. We found that more genes encoding transport-related, muscle contractile, and DNA-associated proteins were changed with HS in soleus muscle from young compared to old rats, whereas more ribosomal and RNA-binding proteins were changed with HS in old compared to young. In particular, RNA binding motif protein 3 (Rbm3), a cold shock protein, was elevated with HS in young by 2.5 and in old by 4.7-fold, however cold-inducible RNA-binding protein (Cirp) was elevated to the same extent in response to HS at both ages. In summary, similar trends in gene expression occur in response to disuse atrophy in soleus muscles from young and old rats, although the magnitude of the changes varies age-dependently. Disuse in muscle appears to elicit a cold shock response which may become more pronounced with age. This work was supported by NIH grants: AG-20407 and AR-47577.