Muscle fiber specific apoptosis and TNF-α signaling in sarcopenia are attenuated by life-long calorie restriction

SPECIFIC AIMSLoss of skeletal muscle mass and fiber number (sarcopenia) is prevalent at old age. The involvement of tumor necrosis factor-α (TNF-α), a catabolic cytokine found to increase with age and with the ability to signal cell survival or cell death, poses as a potential contributing factor to this condition that, so far, has been unexplored. It is not known whether life-long calorie restriction (CR) exerts some of its anti-aging capabilities by influencing the TNF-α signal in vivo. We investigated apoptosis as well as inflammatory and apoptotic proteins of the TNF-α signaling pathway in the soleus and superficial vastus lateralis muscles of 6-month-old, 26-month-old ad libitum-fed, and 26-month-old CR male Fischer-344 rats (CR=40% restricted compared with ad libitum). Hence, this study documents the effects of aging and life-long calorie restriction on TNF-α signaling and skeletal muscle atrophy in a type I (soleus) and a type II (superficial vastus lateralis: SVL) muscle, and reports the TNF-α sig...