Hsp70 prevents disuse muscle atrophy in senescent rats
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This study determined the effects of heat shock protein 70 (Hsp70) overexpression on disuse muscle atrophy in senescent rats. Solei of young and senescent rats were co-injected with Hsp70 plus a nuclear factor kappa B (NF-κΒ) reporter plasmid. After 4 days, the hind limbs of half the young and senescent rats were immobilized for 6 days with the remainder serving as weight bearing controls. Hsp70 protein levels and cross-sectional area decreased in both groups (~20%) after immobilization. Atrophy was prevented in those fibers overexpressing Hsp70. NF-κΒ activity increased in the soleus of both young (three-fold) and senescent (five-fold) animals after immobilization and was prevented by Hsp70 overexpression. Inhibitor of κΒ decreased in young (~30%) and senescent (~10%) animals with immobilization and returned to normal with Hsp70. Heat shock protein 70 overexpression prevents disuse atrophy in senescent rats, possibly through suppression of the NF-κB pathway.