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Stereological analysis of Akt in muscles of young and old rats following a single bout of stretch-shortening contractions.
Rader-EP; Ensey-J; Baker-BA
FASEB J 2013 Apr; 27(Meeting Abstracts):1150.4
Careful design of resistance training programs is critical for offsetting age-related sarcopenia. To address this, we implemented a non-injurious stretch-shortening contraction (SSC) protocol to muscles of rats. Following 4.5 weeks of resistance-type training, muscles of young rats increased force by approximately 30% and mass by approximately 16%, while old rats sustained force deficits of approximately 30% with no change in muscle mass; no overt signs of histopathology were noted. Age-related maladaptation to training may be due to aberrant Akt signaling - signaling influential in cellular survival/growth. Purpose: To characterize volume density of Akt positive muscle fibers following an acute bout of non-injurious SSCs with aging. Methods: Dorsiflexor muscles of 12wk. and 30mo. old Fischer 344xBN Hybrid rats were exposed to SSCs in vivo. At 6h, 3d, and 5d, tibialis anterior muscles were removed for stereological analysis of transverse sections labeled for pan-Akt (N =3 per group). Results: For control muscles and muscles at 6h, pan-Akt volume density represented approximately 40% of total tissue volume and was independent of age. At 3d and 5d post SSC, pan-Akt levels were unaltered for old rats while values for young rats were decreased relative to values for old (p<0.05). Conclusion: While the training-induced decrease in Akt at young age needs further study, the lack of change in Akt levels at old age is consistent with an overall blunted response to training.
Training; Animals; Laboratory-animals; Muscles; Muscle-function; Histopathology; Age-factors; Tissue-culture
The FASEB Journal
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