(The FASEB Journal. 2007;21:922.1)
© 2007 FASEB
Calorie Restriction Improves Skeletal Muscle Hypertrophic Response In Aged Rats Following Functional Overload
Darren Ting-Cheung Hwee and
Sue C Bodine
Neurobiology, Physiology, & Behavior, University of California, Davis, One Shields Avenue, Davis, CA, 95616
ABSTRACT
Sarcopenia leads to losses in skeletal muscle mass and oxidative metabolism. Recent data has suggested a potential link between the loss of oxidative metabolism and a decrease in protein synthesis which might explain the loss of growth following chronic loading in aged rodents. Calorie restriction (CR) attenuates the loss of muscle mass and maintains contractile and metabolic function in aged rats. To date, however, no studies have examined the growth capacity of aging muscle under lifelong calorie restriction. The objective of this study was to investigate whether calorie restriction improves the ability of aged skeletal muscle to hypertrophy under chronic loading conditions. Muscle morphology and activation status of the Akt/mTOR protein translation pathway were examined in young adult (8mo), old (30mo), and old calorie restricted (30 mo CR) male FBN rats following 14 days of chronic loading. The plantaris muscle was functionally overloaded for 14 days following bilateral synergist ablation of the soleus and medial/lateral gastrocnemius muscles. Plantaris muscle growth was significantly greater in 30 mo CR rats as compared to 30 mo rats in both control and functionally overloaded conditions. The data analyzed thus far suggest that calorie restriction allows for an improved ability for old rats to hypertrophy after 14 days of chronic loading possibly through improved oxidative capacity and protein synthesis.
